Yes,

Install these two games:
Arma 2
Arma 2 Operation Arrowhead > NOT THE BETA

Then after that open both games and close them.

Install Dayz commander and install the map you like
And d ...

Ask if a admin can help you out, did you tried jump and run through the wall? sometimes when you do that you get out of it.

Do you have installed the Operation arrowhead Beta? if so, delete that game it will update OA to 1.63 version and you need 1.62v

I agree with Gigahertz, You need alot of patience for Dayz.

And Dayz standalone is in Alpha version so try the mod again, play it with some friends it will be more if you play it in a team.

Or ...

Try to play with the settings.. Maybe it's a lil bit to high? I never experienced the lag in the standalone version.. but maybe Xbox_one is right. it is still in alpha version.

Play the mod instead ...

Nope you didn't spawned it. Just drop the ammo somewhere in the woods, and if you get killed other people will think you spawned the item and you will be banned from the server then.. probably..

40 fps and it drops in bigger towns to 30fps

Yes, But i think you can't play on ultra settings with these specs.. still a great game with lower settings!

I am using these specs
Intel Core i5-4570 (3.6Ghz)
GeForce GTX 550 Ti
8gb of DDR3
...