Q:

Approached for Interview | Currently employed & Have a Personal Enterprise

Recently, I have been approached by a company to interview for a position very similar to what I am currently doing (albeit wider in scope). This is for a much smaller company (approx 35 total employees). The company has grown a lot in the past 5 years, and has been around for almost 30 in total with stable growth until it "exploded" due to new management. They have described themselves, as being in almost a "start-up mentality" (their words not mine) as a result of market and product diversification, and rapid (albeit safe) levels of growth.
Now, as I alluded to earlier, I am currently employed. The new position is in a different enough sector that my non-compete does not apply so there is no conflict of interest there or anything of the like. However, I do have a few concerns about somethings raised in the interview and some questions for potential changes to my life as a result of the new position.
Interview
The interview, I found, was quite disorganized. One person called in (and was just on speaker phone). While the two that interviewed me in person (for a Purchaser position) were the President and Controller of the firm. All of this for a small company didn't raise any flags. What did however, was the disjointed nature of the questioning - jumping from technical skills, to computer literacy to "what-if" questions, to task management and back again. I have never had an interview that "bouncy" before. And I know, it wasn't due to them trying to keep me on my toes because all three of them had a lot of dead air, and "uhm, uh, hmmm" between questions as if they didn't know where to go next. Also, I asked once on the phone and once in person what the scope of the role was, and they volunteered an explanation as well (so 3 reviews of the role in total) and each time it morphed into something bigger. Which gives me pause, that they don't have a clear vision for this position. 
My Interview concerns are:

Does the disjointed interview process give cause for concern or is that more typical in smaller organizations?
Does the consistent change in description of the role give cause for concern?
Also, they brought up money (how much I want to make) three times in total (once on the phone and twice in person). Is this a worrying trend? Or normal when going to a smaller organization?

Personal Issues
Last week, I asked about Starting A Company - While Currently Employed. Now this position was not known to me when I wrote that question. As a result, I didn't frame it in such a way that the answers really solve the situation here.
Say, I were to take this job, there would be no conflicts (again different sector), the hours would be roughly the same to what I have now. How would I go about partitioning time while starting a new role, and continuing my company - so that I don't give the impression that I am already planning my exit (which, honestly even if I don't take the position I am not planning on an exit due to my company).

A:

It sounds like they are trying to hire into expertise that they fundamentally do not have for themselves.  They've been rapidly expanding, and they've realized that they need someone in a role as "experienced blah" for your particular blah, but that very need means that they're not sure what that entails.  They don't know what they need you to do because they don't understand the thing that you do all that well.
This could be good or bad.  The uncertainty in your role might mean that you can define what your role is to a high degree, and focus on your areas of particular expertise.  On the other hand, if one of the (few) people above you is of the "highly opinionated shouting about things they don't understand" types, you might find your role being regularly redefined, or redefined into something impossible or retroactively defined to include some aspect that you were never informed of.
They money thing is them trying (in a somewhat ham-handed way) to nail you down on cash.  Recruiters and HR people pretty much all do that, though these were apparently less smooth than others.  It may also feed into the above.  It's possible that they literally don't have any idea of what you are worth, and are trying to flail around in the hope that you will offer them a number.
There are also some factors particular to your situation that I would mention, however.  The first is that startups often want to consume particularly large percentages of available time and energy.  That might conflict with your idea of starting your own business.  If you're pretty sure that's not going to be the case, though, it gives you an opportunity to get a contractual exception carved out for your business from the beginning, thus eliminating any issues (legal or otherwise) that might come out of having it discovered later on.  If they really want you, you can get a job that's customized for you to grow your business next to.  (For example, have you considered offering to work for them part-time?)  If they don't really want you?  Well, if you bring it up to them and they balk, then you haven't really lost all that much.
My personal suggestion... think about what the perfect shape for you would be for this job (hours, money, etc).  Be generous with yourself in terms of money, but not absurd.  The next time they ask you about money, push that as a proposal.  If they basically give it to you, that's a major win.  If they back down, then you still have your old position (which was serving you well enough up until now) and you haven't really lost anything.

A:

I have been approached by a company to interview for a position very similar to what I am currently doing (albeit wider in scope)

You appear to have been approached based on your current skills/accomplishments based on publicly available data about you, and apparent eagerness of the organization to have someone with similar skillsets.
From your description it also appears that the company believes that someone of your calibre can steer it in the right direction. They however, seem to be laking the complete insight into the role.

Does the disjointed interview process give cause for concern or is that more typical in smaller organizations?

It should be a cause of concern for you. How well is the position described to you? How well does it aligns with your future career prospects? How well do you understand the business and current position of the company? You need to get answers for these questions.

Does the consistent change in description of the role give cause for concern?

It very visibly indicates lack of clarity as far as the management is concerned.

Also, they brought up money (how much I want to make) three times in total (once on the phone and twice in person). Is this a worrying trend? Or normal when going to a smaller organization?

It further solidifies the fact that they are looking for someone of your skills, without complete clarity, hoping that you can be a very valuable addition and for whom they might not have the budget.

It would be advisable to learn as much about the business and the plans of the company. Do a reverse interview and see if they are able to satisfactorily answer your queries and make your move based on how satisfactory the responses are.

