All was cut/ripped out and, I imagine sold for scrap to support someone's habit. 

I did it as a very experienced GC and still lost money one time.If you still want to start off flipping, then go with an easy one.....just needs flooring /paint/appliances/toilets/etc......

If so and its lead paint they will ask you to remediate.

I recommend they buy a trailer or a house hack that requires a paint job and a new carpet.  

I know a teacher who has a house painting business he runs on the side/ in the summer.

For rental to be in same condition when rented by tenants, I will need to: touch-up paint, clean house, wash windows, clean carpet.

And lets face it, when you ran your numbers you should have already figured in the cost.Now if its just cosmetic, paint, flooring, etc, no you don't need a GC. 

If you don't and the seller feels "ripped off" after you assign it and make a profit, they will come after your license and have a good shot at it.This also makes it more challenging to be fair, honest and ethical with a seller.

Even the type of wood floor, tile, different colors of paint, bath fixtures, lighting etcAlways give specs and be very specific as you mention, otherwise it can cost you later on down the road

A low-cost way to do it would be to paint the walls, the garage door, and close off any access to utilities.