Hired as a research assistant and told to track working hours for payment, is this normal? I have been given a great opportunity to work as a research assistant. I will be working under this researcher (and her team) for about 5 months. I was only suppose to start in mid-January. But she said she would like to hire me as a research assistant for the next few weeks (full-time). She said she will be paying me (and the rate /hr is surprisingly high). Come mid-January (when I was suppose to start) I will not be allowed to be payed for my work (school rules). 

Anyways, this work can be done anywhere (I do not need to be in a specific location to do it). Thus, she told me to track all of my hours and then send her a bill in January. I guess, sort of like what contractors do. I have never had a paid job before, let alone a research position. I am wondering, is this usual? 

I could potentially earn 2 000 dollars over the next couple weeks. However, I feel like this is too much money. I feel as though I should understate the hours I worked. However, at the same time if I did that she would know I didn't work "full-time". This is all new to me so it would be great if someone with experience can make sense of this for me.
From my experience doing research assistant work at a state university in the US, and from speaking with peers in both "hard" and "human" sciences this is par for the course. A tiny bit of paperwork (a signature or two), and away you go. Though I'm assuming by "she will be paying me" it will be through the university rather than out of her own pocket. 

Do the work (well), do not understate your hours, and enjoy the paycheck when it arrives. I can almost guarantee the researcher is concerned about getting things accomplished in a timely manner, and that the cost of your time is minimal compared to theirs and the other costs associated with the research.