I don’t have an STR myself but have helped a friend set up and manage a couple last year and it’s not as simple as it used to be. 

It's simple economics.

Can I still do simple 4 box calculation? 

It can be a simple one page contract b/w you too at an agreed upon rate.

I know I can go through a lawyer but I was told it is a fairly simple process hence want to DIY.Regards,Xuming

Here is an article i found with a simple google search: about $5000 but i thought quiet title in georgia was actually higher.Tax Deed Services For Owners of Tax Deeds - Gomez & Golomb LLC

Your mentor has needs; try to meet them and develop a mutually beneficial relationship.A mentor can benefit your growth, but it's not as simple as one post on a forum full of strangers.

It could be something as simple as a toilet running. 

Do plenty of research and find out what other mistakes have been made in your are and learn from them.Both are great options but maybe doing a simple pros/cons list for both STR and LTR.

Plain and simple, knows his stuff.