For a home defense handgun, it's tough to beat a Glock 17 9mm with a 33 round mag and flashlight attached.
By all means, go to a range, try out different guns, and take some training. It's a lot of fun and you will learn a lot.
Buy lots of ammo for practice. Not just a couple boxes, I mean a couple cases. You have a lot of learning to do and there's no better teacher than practice, practice, practice. Yes, it's going to cost a lot of money.
If you are married, take the wife to training classes too even if she doesn't want to learn how to shoot. If there's a gun in the house, she needs to be up to speed on gun safety.
Don't be one of those guys that buys a gun, shoots half a box of ammo and calls it good.
33 round mag... you bet. The average self defense/home invasion is usually against 3+ intruders. You will need more than 5 rounds, so bring enough for everybody plus a few more.
Check out www.ingunowners.com
Great form here in Indiana and we have lots of members from other states too.
Good luck!