I wouldn't take much stock in what your realtor recommends, they typically list higher than what it's worth to lock you into the deal  I use flat fee and can sell myself or MLS which works very well for me in the event I do a creative sale. 

Typically if its owner occupied, 20% down will suffice.

It works ok in some areas but apartments will typically rent for less than houses.Last, I didn't see utility costs. 

This includes FHA, VA etc.For non owner occupied investment property typically it’s 15 percent down minimum for Single family and likely 20 or 25 percent down for duplex, triplex etc

Salesmen typically try and sell what they have in inventory and badmouth the items they don't have access to.

Although the Killeen area is much more affordable than the Austin area, prices are still a bit high for cash flow purposes on typical SFR homes.

The cost is higher and there are typically more exclusions on those Excess Lines policies. 

Also, what's your suggestion on closing schedule for multi family apartment typically?

I posted about this experience recently: https://www.biggerpockets.com/blogs/8160/71180-we-...With a master metered property, you have a few options: (1) you become responsible for the water bill and include a flat fee in the rent (2) sub-meter the property so each unit is on their own meter, making the tenant responsible (typically VERY expensive) or (3) implement Ratio Utility Billing System (RUBS), this is where you are still responsible fo the water bill but through a formula and spreadsheet bill back the tenants their fair share.

Also, with Section 8 tenants we typically see higher R&M.