Q:

Why is there an à with "visant à"?

Le RAFEO est un programme d'aide financière visant à vous aider à
  payer vos études au collège ou à l'université.

I want to know why there is an à in visant à.
None of the entries in the wordreference page for [viser][1] is an entry for "visant à". My guess here is visant à vous aider à payer .. means "aiming to help you to pay..".
The relevant entries in wordreference don't have the preposition "à"; the example sentences also do not have the preposition "à":

Simon vise le poste de directeur.
    Simon is aiming for the
  manager's job.
Cette loi ne vise que les étrangers.
    This law only targets
  foreigners.

Questions:
1a) How come there is an à after visant, in "un programme d'aide financière visant à vous aider"?
1b) How could I have found out what visant à means, using a dictionary?
1c) Is "visant pour" allowed here, instead of "visant à", considering that "pour" is the preposition used to mean "for the purpose of.." ("aiming for the purpose of helping you pay..").

A:

Your translation is correct.
1a) There's an à because there is indeed an expression viser à [verbe] "aim to do", which is an omission in WordReference.
1b) Unfortunately in this case you'd have to check more than one dictionary and hope that one of them has it. In this case, Reverso does:

viser à         v
avoir pour but de

I realize this is frustrating since it suggests that any time you don't find an entry, you might find it in another dictionary. I think that would be fair to conclude, though I tend to use different dictionaries for slightly different purposes to reduce redundant checks, and your choice made sense for a two-word entry - I'm surprised that WR lacks this expression that Reverso has. I just used their "signal an omission" form to request this entry.
1c) No, not only because (as you now know) viser à is a fixed expression, but also because the construction pour [verbe] is better translated "in order to [verb]". Hence we'd get something like "aiming in order to [verb]", which doesn't work in either language.
On the other hand, you could say, for example, « viser à terminer avant 15h pour vous permettre d'attraper le bus » : aim to finish before 3 p.m. in order to allow you to catch the bus.

