Regarding your plan;  The plan to purchase a multifamily, live on a portion & rent out the rest, then  continue to do that as you move, is a great plan.  

that I bought for 378k, we live in the smaller portion.

Mezzanine debt typically has a higher rate of return than senior debt but lower than equity.Preferred Equity is perhaps the hardest portion of the capital stack to speak about generally because it’s, for better and worse, very flexible.

Depending on what town and the size/condition of the apartment, you might be able to get more than $1200 a month for a 2 bedroom with the lack of available rentals on the market currently.

I have been asked for this on both income and comparable sales refinances, however on comparable sales it has been a criteria of the lender not a portion of the appraisal. 

I forget the exact statistic, but there is a good sized percentage of credit scores/histories with mistakes on them.Heck, I currently have two past 30 day late payments on my Home Depot credit card. 

Will this likely change things or will they go back to that old size?

Doorway landing and retaining wall concrete portion finished. 

Do any of you happen to have a spreadsheet that will calculate a particular tenants portion of the water bill considering the number of days they have occupied the unit?

Knowing the size of the loan might get more specific recommendations.