If your current income is low, just be extra careful when evaluating the repairs needed on fixer-uppers and you should be fine.  

I think if you could easily pay that extra bill during the process of the flip (Research, closing, renovating, and listing), then I say go for it.

With private schooling comes extra associated costs.

ive been contacting people with ads on craigslist for houses for rent.

If possible, I will also be renting out the extra bedroom (if there is one) in the unit I will be occupying.My questions: To learn the ways of land lording, does anyone suggest doing a du-, tri-, or quad-plex over the other?

I read a lot of books and threads regarding the importance of Due Dilligence for the apartment buildings.After the proptery is under contact,I will definitely do the detail due dilligence in person and with propterty manager or contractor.But still I have the concern that before I put the proptery under contract,if I am in long distance or out of state,how could I do the due dilligence to do the pre-acqucition analysis (repostition chance,how much value can de added)?

I will ad that you should talk to multiple agents first to see who is even receptive to the reciprocation with you.  

Why should I look into short sales for adding to my investment portfolio?

You've got to be either dragging a lot of extra info the main ledger to support sub ledger functions or you're missing details you could use for reporting because youre main ledger can't support all that information.

Adding one property every couple of years.