K.C.
Wow, that's alot of information :) I can tell you've done your homework. Honestly, I would put the $7k in an interest bearing account and forget about it. Within a few years, you will have accumulated enough interest to do what you want (down payment on a house, buy a car, etc) and still have some leftover.
Most financial experts will tell you that paying off a car or house is the last thing you want to do with extra cash. Homes and cars usually have low enough interest rates that your payments are a majority towards principal. They recommend paying off credit card debt (if applicable) because of the extremely high interest rates.
You might want to consider refinancing your home. You said you closed at a rate of 6.25% five years ago, but the Federal Reserve has reduced rates significantly in the last year - you can find a 30yr fixed with a rate as low as 3%!!! Don't forget though, that you will have closing costs, so unless you can get 2% or more lower than your current rate, it may take some time to "break-even". Usually you can get a cash payout if you refinance at a reduced rate. You can either put that money towards the principal so you'll have more equity in your home when you sell it, OR you can use the cash to fix up your home so you can have a higher asking price when you sell.
Don't forget, the real estate market is at an all-time low right now, which makes it great for buying a house, but not selling. My husband and I had to move to Dallas for his job. It has been over a year and our old house still hasn't sold - and it's a beautiful home (I miss it). So, we are paying 2 mortgages, utilities on 2 houses, etc.
Believe me, my pockets are ON FIRE when I have extra money, but since my little one has arrived, I really am making a huge effort to save and put money away. The economy is so screwed up right now, I feel I'm best off just burying money in my backyard :)
I hope some of this helped. Congrats on your bonus, but more importantly congrats on your pregnancy. Maybe you should put $6k away in an account, and take $1k for a great vacation for you and your hubby!