Thank you for your question.
1) You will have to put down at least 20% in most cases -- you can get away with less if you qualify for an FHA or VA loan.
2) The loan officer will want to see less than 45% debt to income -- that means, the total of your debt payments including mortgage should be 45% or less than your income.
3) Get pre-approved with a lender. I favor Wells Fargo since most loans get sold to them anyways.
4) Short sales are frustrating - and can take a while to close. This is because the lender must approve the sale and they can reject it.
5) When shopping for a home, you will simply have to do research in the areas you are looking -- see what recent sales in the neighborhood are like. Get a home inspection and include in the contract that the inspection must be clean.
Here's a good guide to look through as well:
Please let me know if you need anything additional. If not, please rate positive.