3-  In a smaller job probably you can sub it out but in a big job you need experience to see how to co-ordinate different subs at different times and you won't be an expert, the contractor is. 

I’m no expert but I can’t imagine a bank saying no.

@Brittany Kuschel is an expert in the area, I would recommend connecting with her.

Can anyone as an expert please tell me if I should buy or just keep renting?

If you’re holding a rental duplex in your name, I would highly suggest you move it into an LLC (with the assistance of tax / legal experts) to protect any liability claims spilling over into your personal space(home, car,  investments).If you’re investments are large enough it could make sense to create a separate S-corp to perform management services that would have some tax advantages over having those fees performed by an owning LLC.  

I need some guidance/advice from experts.

Also, make sure they are experts in managing what you have in your portfolio.

If you hit one or two ripe markets hard you can be the expert there and really penetrate the market.

Basically don't expect an executive housing agency to expertly handle section 8 properties and vice versa.  

Wanted to run it by all the experts on the forum.