QUESTION:
I want to get the houses under contract first then find the market rates. Should I do it this way? If I find out that the market rent rates are not in line with the seller’s mortgage, can I redo the contract between the seller and I?

ANSWER:
I would always get the house under contract first. Consider this, the place your paycheck is coming from is the tenant/buyer. So, what’s your asset? That’s right, the house they’re looking for.
Two, yes get a good idea of rent rates first. Not a hard thing to do since it’s only a phone call away from a management company. (Many realtor’s are management companies too) Find out what the average 2/1 and 3/2 (three bedroom two bath) go for. Then you’ll have an idea of what’s going on in your neck of the woods. Don’t want to make the call? Look on craigslist and the local paper and Internet. Done.
Hope that helps.
Adam