I've done tons of homework and have one specific question—my realtor is concerned that if I purchase a home in the next few months I will be selling in the fall/winter, when the housing marked noticeably cools.Do you, smart readers, recommend putting the project on hold until I can sell in the spring/summer?

The best accuracy is the NOD, Notice of Default, posting at the courthouse usually.

When my friend, the builder, sent over the contract, I noticed in the contact a $10,000 developer fee to be drawn up to $2,000 per month during the construction period.

If their tenant is having a moving/garage sale, if their property looks untended, if they are receiving default notices, etc. they hear from me.  

At that point, he gave me a thirty day notice to move out. 

I just noticed you claim to be a turn key provider.  

I would serve notice once they are 5 days late.  

This isn't really something you can ask too directly, you don't want to seem like you're setting him up to be discriminated against, but if you're observant, you'll notice pretty quickly if he uses home health services, has a social worker, etc.

And I never would've noticed, had I sent it to a company to write and mail them (which I will do next time). 

I would think someone would notice 11 units in 2 houses.I think the only safe offer strategy would be based on restoring to SFHs and selling on the retail market.