I know Fannie Mae typically requires 90 holding period before I could flip a Fannie Mae foreclosure but what about VA?

You might consider both (asking for references, and scouting the early bird material buyers in different sections of store) so that you have contacts for quick-and-dirty jobs, as well as larger projects.  

May be he is looking to sell quickly for whatever reason and 100k cash looks appealing to him than waiting for 30-45 days for commercial loan to close with no guarantee.

When I go to Lowes I know everyone there and they know me, the in-store commercial guys will call me when there is clearance/closeout stuff they think I might like, and due to my volume purchases I have a good relationship with the regional sales rep who stops by my office for periodic visits and is a great go-to when I'm not getting the answers I want at the store. 

If you have discretionary cash, lines of credit and 401k borrowing for plenty of quick cash, what is the top strategy to put them all to work?

Chatting with a few professionals in the field will be the best way to ramp up your understanding quickly.

If you serve a 60 day to quit, you are still entitled to the rent for the unit until that 60 day period expires, the 3 day to pay is there for that reason.

The only problem is the his house already went through sheriff sale and it's on the redemption period.

I'll try calling you tomorrow for a quick chat.

You have to really know the market and act quickly.