I am working with a new investor that is considering multi families in the $2m-$3m price range. 

From this data, you can utilize a website bestplaces.net that will give you a breakdown of the percentage of homes that sold, in various price ranges, for a given zip code.

I would start here because these residential interest rates are significantly lower than other options (usually adjustable in the 2-4% range) in terms of the fees and interest rate.

Also what is an ideal range to shoot for? 

If it was from sale of a business or similar, I would probably invest it in BRRR and flips on a 1:1.5 ratio in the 60-80k per house all in range.  

If you can leverage up then 20 to 50 million is a nice business you will make about 1 to 2 million a year if you won the company.it sounds like you have zero experience so HML is probably far to risky .what I would do if I was you if you have a million or two .. use an established HML to place loans for you in their network and shadow it learn what they know and how they vette then after a few years go on your own.HML at the 100 to 200k range as an example is a waste of time not enough money in it at least for a business to eat off of.

The factors I'm thinking about range from "location", "amenities", "used vs. new", "lot size", "pool, etc.".

I'm not a lawyer- but your interest can range as low as 1/2% to 99% - best to check with others here :-) My attorney has done deals as low as 1/2% - and it has held up in court ( he helped pass the rule in a Superior court case here in Georgia a few years ago).

The roof is in need of some repair (~$2000), but should probably be replaced entirely in the 3-5 year range for roughly $21000 (huge roof).

Is it safe to assume numbers in those ranges when evaluating a deal for buyers?