Bob,
you are smart to plan to just stock one type of ammo. 9mm being the most common other than the .22lr
a glock would be a good choice as it is reliable and it holds lots of rounds. Dont be side tracked with the argument that 9mm is not a good caliber you need a bigger caliber and so on. If you can carry more rounds it is your advantage. and you know if one round dont stop the aggression, just put in a couple more rounds. two is always better than one and three is always better than two. and so on. Plus depends on where you put the rounds on. So if your aims are good then it will take care of the problem.
also 9mm is cheaper than a .45 . So with the same amount of money you can stockpile a lot more 9mm ammo. 9mm being more common meant that if you enter a house to scavange for ammo you will probably find 9mm as most household has them.
Now a glock is great but i would suggest getting a few other handguns also. Just go with cheap ones. like Hi Point which can be had for 160 bucks. Or kel tecs which are very well build guns and cheap. You should have a couple of backup 9mm handgun incase something happen to your primary handgun. Hi Point has been step on and people call it a piece of trash and they are ugly but they are virtually indestructable and would continue to shoot. It is not pretty but it is cheap and it will work. I have a Hi Point handgun and it work after thousands of rounds thru it. never jam once. It only love ball ammo however . so no hollow points.
The baretta Cx4 storm will be a good choice for a carbine. There are just alot of types and brands out there. But pick one that you can buy magazines cheaply and most available. and get one with lots of rounds per magazines. You need a lot of magazines for your handguns and carbine. Because in a firefight it is all about who has the most ammo to outlast the other.
That being said. I would suggest getting a shotgun also . a mossberg 500 would be an excellent choice.
Also you probably want to have a rifle round (centerfire) or some sort incase you want to go hunt for food. But a mossberg shotgun can also be use for hunting. So if you want to stick with one caliber then the 9mm will be great. But I suggest a 12ga shotgun also.