On the rehab cost build in a margin of at least 10k but ideally more like 20k and verify with a contractor.

It would be different than if the rents were 2k+/month on average. over time I think it's good to do your own maintenance (you'll need to build a team for this) to save on that 10% along with the other margin they add in there.

I remember starting out years ago in the military so even making a marginal, positive impact would be rewarding.After two weeks in searching, there is three houses I am drawn to.

If not, a management company would essentially kill any margin you were making.

I see a lot of marginal deals (12-18% project IRR) being marketed by less experienced syndicators and I am worried that their passive investors will likely lose money as cap rates start to decompress (and cap rates will decompress - it's just a matter of time).

It's called piercing the veil.This may not apply to you since you own the home outright, but in today's market with the margins on properties being so thin I personally wouldn't want to assume the extra cost for only 1 property. 

She is an attorney so is able to easily fight the property taxes herself through the system without having to hire anyone else to help her but only has marginal success.

On very basic starter homes is there enough profit margin to refinance out your costs and keep it as a rental with no money stuck in the deal?

Not to "do your homework for you," but this is fun, let's take the GPT suggestions above from @Kristi KandelVersaStorage: Vehicle Parking and Self-StorageLong-term vehicle parking is what you do, that not everyone does, so it comes first, when markets find equilibrium you will find higher profit margins on that, for that reason, so that's the priority.

However, if you purchase in a location where rents outpace inflation and there's rapid appreciation, even a marginal first-year deal can become a killer deal over time.