If it works for you, I think you can usually do better(cheaper) buying an existing house over having one built. I'd keep a comfortable cushion between housing expenses & income/assets.

I'd also want to put some $$ down, to at least get under the PMI level. We all have different thoughts & comfort levels with home loans, interest deductions & the rest. One should have some room in the budget for retirement, unexpected auto/life expenses, 529 plans(if required) & the other things.

I have USAA for a few things, mostly insurance. It may be a bit cheaper elsewhere, but I'm happy with them.