For your smaller deals (less than 30 units) using a 10% vacancy/collection loss factor and a 55% expense ratio is a pretty good place to start the analysis (might be a little conservative from a V&C standpoint).

Do you factor in the 1% rule for initial asking price or for the ARV amount to predict cash flow?

Regardless, there are numerous factors that would affect a correct answer to your question. 

Make sure to factor in floor insurance if you buy on east side of grand parkway.

@AP Horvath cap rate is going to have quite a degree of variance depending on multiple factors, 3 primary variables being:Asset class type (A, B, C, D)Property condition (turnkey vs value add)Location (especially with property taxes here)Again, it varies on the factors above and if you are calculating your cap rate via purchase price model or projected price model.  

I think the class of property/tenant is also a factor on where people look for apartments.

I would be very cautious about this and DEFINITELY not take anything that realtor says as fact....or that they are telling you everything.

They can also go back farther in time, and do an appreciation factor. 

Will depend on several factors like the type of property, type of tenants, your risk tolerance, other assets you own, your estate planning, laws where the property is located, etc.Any lawsuits would be limited to the assets of the LLC and not your personal assets (assuming you run the LLC appropriately and the corporate veil is not pierced).

I've found that when looking at properties quickly it's safer to assume 60% of rent will be expenses (prior to factoring in mortgage payment -principal and interest-).