You could do that and refi it and save some down payment money, but you'd have to shell out $100k+ for 6 months to do it, just for a 15-20% discount to value. 

Also, the question of what discount rate to use is important.

If you buy these properties you can buy them without title insurance (presumably at a deep discount) which I would not recommend except for extremely knowledgable and experienced investors.If you're willing to buy the properties with title defects and cure the defects, go purchase at the tax sale yourself and cut out the middle man.

I do not give a discount.

Before then, enjoy the tax discount.

Just because they moved out early, I don't think entitles them to a discount unless you were able to secure a new tenant before the 1st of the month.As far as taking it out of the security deposit, I think this is a good example when that would be acceptable.

If not, seek a discount.  

When" buying", I seek out discounts from 1 to 1and 1/2 percent as a "cash back".

Typically, kitchens and bathrooms will give you the best return, but each market is different, so some background work is required.4) If you do not have the time to list the properties, why not use the friend for a discount, but as Jacob said, that is assuming he is good.

They don't require a separate trade (HVAC) your electrician can handle them, they don't need to be installed until move-in if your worried about theft.Craig's list is excellent for appliances, don't discount some of the low end stuff at Sears.