I’m concerned about the long waits and the timing required to get both my mother and the unit approved.

This isn't meant to be preachy but others might come across this post and wonder how to prevent it.The two biggest areas of concern here are...Your loan amount. 

My AGI is above $100k, but I'm not too concerned with taxes while working my W2 job.

You can get duplexes with a Seattle address in the $500,000 - $1,000,000. 

Should be a good learning experience without the concern for time.

After a period of "they are not a hassle" I am willing to lengthen the lease but I am not concerned about people moving in and out all the time because my market does not have many rental opportunities right now. 

I’m finding in New Jersey were about back at 2007 levels (which is concerning imo), but interesting enough my father in law is trying to sell his new construction purchased at the peak of the bubble down in Columbia, South Carolina and it doesn’t look like he can at least break even, not even close really.

As far as the Cap Rate is concerned. 

If you use a Fannie/Freddie loan, transferring the property to an LLC could cause due-on-sale concerns. 

Just send your email address and I can share their contact info.