I think just typing some of these questions has already started to help paint a more vivid picture.

Once you do, the picture will be clearer on where to invest and what to invest in. 

Paying a contractor double this.

An alternative would be to let the tenants continue to pay down the mortgage and add another rental when you can letting the tenants pay for that mortgage or doubling down the payoff on the one. 

I'm young enough to look like I'm in high school (just look at my profile picture!)

Or it could double like this random house in my city did since it's 2006 sale price:https://www.redfin.com/WA/Kirkland/134-8th-Ave-980...So you have to decide if taking on the debt is worth the potential reward, including your specific scenario limitations. 

From what I've read you have to basically pay double on rental properties.

The risk is the buyer/seller would your fees and most of the time under $5000 or may be upto $10,000 fees; buyer or seller will let go.When profit starts to go ovr $10,000 or 10% of property price; you do double closing OR simultaneous closing; then it is better to use transactional funding from lenders; who do 100% financing. 

I am just starting out, so I don't see the whole picture of multifamily business.

Do you provide move in and move out reports How many pictures do you take of the property prior to tenant moves in and after the tenant moves outDo you get weekly reports when the property is vacant what prospective tenants are saying about your homeDo you provide monthly newsletters to your tenantsDo you hold investor education classes to help me become a better investorDo you have single point portfolio based management services?