I want to make an offer on a REO using a LLC (or whit a S Corp ) as a purchaser, once they accept the offer I will sign on behave of the LLC in order to get the contract, now that I secure the deal I will talk to my possible partners (I have already 6) investors to join me and I will let them close using the same LLC but at this point I will transfer it to them for a finder´s fee plus we will draw a JV agreement in which will state that we will split the profit at 50% on this way they will have the security on been on title and I will get the security of gaining my profit.Can this be done on this way  ?

If the tax sale was before the foreclosure, then the bank must redeem from the tax sale before they can sell the property with good title.

The real estate attorney I use for title and closings advised that I need signatures, but I'm not convinced.

Title is currently in the name of the deceased wife and the 2 brothers. 

Typically, when you get the P&S executed, you will forward it to a investor friendly title company that you have already contacted.  

If add my dad (also foreign national) as co-borrower, in what way I can remove his name from the title?

Do you work with a title company?

well, title is free and clear.  190-195 is the ARV

Do I receive a clear title at closing and are all these fees paid before closing or will I only know this upon receipt of the contract? 

If the property is held in the name of decedent, you'd need a RM balance leaving sufficient equity to cover the costs of the title fix.....which assumes there are known heirs whom can act as admin/exec in a probate action.