And I would only flip upper end condos, I've seen several people get stuck with sort of middle class condos.

If the plumber they used went in there and just snaked it, that would have been all they had known.Unless you can find some sort of smoking gun proof that the former owners were told by a plumber that the drain pipe was put in wrong and needed to be fixed, I don't see any way they could be held liable.Unfortunately, its just called a piece of bad luck.

Its probably RT4 or RT2, which means a maximum of four units or two units per property respectively, but of course all sorts of other rules come into play too like setbacks, etc.Definitely be careful when buying this bulk purchase as far as taking on properties with code violations, which nearly any REO at least in the city will have because they inspect them all and meeting exterior code to the letter is essentially a like new house.

Again, this sort of depends on type of lender which it's not clear which is suitable.

Especially if you get any sort of snow, ice, or wind.

I inquired on financing for a 12plex and the lender, a local bank, offered several options, one of which was pledging one of my free and clear 4plexes as collateral for most of the down payment, and then about 5% cash from me to have some "skin in the game" (his term).I was unaware of this option, and thought that was pretty aggressive.

@Jon Klaus is correct...that's sort of redundant.  ;-)Richardson, particularly west of 75 is a great flip area. 

You learn to get thick skin though, now I have to laugh.  

If your father is willing to shell out a significant amount of capital for you to get started and your true goal is to be a real estate investor then you need to be present every minute of the process and involved in every decision along the way.Finally if you do decide to partner with someone make sure you do not put up 100% of the cash and that they have skin in the game as well, make sure you are on the title and have a clearly defined JV agreement drawn up by an experienced attorney

Aside from any investments that I would have my own skin in, I am a fan of REITs made up of holdings of well known (and public) companies.