Granted, if you find large, unexpected items during your diligence that you could not have reasonably known about you might consider taking it up with the seller, but most of the things you listed are minor.

Download BP’s newest book here some good due diligence in Chapter 10.

Here you will meet wholesalers who provide deals and all the cash buyers (rehabbers) you will need.Download BP’s newest book here some good due diligence in Chapter 10.

Never make quick decisions on any investment in real estate, take your time do as much due diligence as your conscious/heart desires.Is this a good approach to receive Passive rental income (or) should I search the properties and do all the work myself?

Download BP’s newest book here some good due diligence in Chapter 10.

Here you will meet wholesalers who provide deals and all the cash buyers (rehabbers) you will need.Download BP’s newest book here some good due diligence in Chapter 10.

@George Smith  Your post is a bit too wordy and you misspelled 'diligence'

Scott The Book on Flipping Houses, The Book on Estimating ReHab Costs http://www.biggerpockets.com/flippingbookConsider checking out HUD homes for small multi's owner occupied gets first crack.Download BP’s newest book here some good due diligence in Chapter 10.

My question is what are the absolute must-do things that I have to do during the due diligence phase?

Here you will meet wholesalers who provide deals and all the cash buyers (rehabbers) you will need.Download BP’s newest book here some good due diligence in Chapter 10.