Is it easy to manage a SFH rental property here by yourself considering the risk of delayed rent,  eviction possibility and ect?  

It is a totally separate policy (builder's risk).

If you make  that choice you need to understand the risk you are taking. 

and also your risk tolerance (how much debt and at what rate do you tolerate?

It's those maniacs that buy homes cash via quit claim deed off of craigslist that really get screwed.Make sure your property manager is a licensed real estate brokerage.Understand you can not eliminate all risk, only mitigate it.

I know the current owner very well so I could introduce this now but would I risk a closing delay?

In addition, I’d recommend going to real estate investment meetings in your area, making friends, and exchanging work for knowledge (or some similar arrangement) so that you can supercharge your skills without taking too much risk (see the BiggerPockets Events page, or google the topic).

Luxury Vinyl Plank...HD carries LifeProof which is great, just remember is you are using in a rental, the warranty is null and void.You want something that is at least 4mm thick.

The first couple of deals, we did a 60/40 split, with him getting 60% of the profit, because he was taking all the risk, and we didn't have a track record together. 

This is too much load for a 60-unit to carry, and certainly not 20-unit.