Is credit score of 719 as good as 720?
It depends on all the different variables... but once you hit the 720 score it can allow you better rates... not by much but it can

First Time Home Buyer in Virginia Question...
As long as you can show a 24 month work history... same job does not matter. If there are any gaps... you will have to explain those

Can I qualify for VA streamline refi with a 612 credit score?
There may be some lenders that can... is 612 your Fico or mid-score?

if I buy a $225000 home with $45k down, how much PMI would i probly pay?
There would be no pmi if you go conventional... If your concern is pmi.. you could also put a less amount down and have lender do a lender paid upfront pmi to save you some cash in your pocket also and get the same result...