I have a handful of airguns, and I don't think I have seriously used or looked at any of them since I because accustomed to the gas ram. I did put about $60 into a good tuning, but it is fun to shoot, accurate, hard hitting, and reliable. I don't know of a fixed-barrel gas ram, but it might be out there. When I was shopping for one, I was inquiring like mad about a side-cocking gas ram, and just came up empty handed. As accurate as I have mine, I do think a fixed barrell version would be better still. And, for what it's worth, mine is a Crossman Nitro Venom Dusk - made in China. I'm not a fan of Chinese either, but Crossman customer service and warranty is rock solid.
On ammo, I would probably suggest .22 over .25, especially if you're just going to be plinking. A wider variety of ammo that is more readily available, and regardless of the brand or style you end up with, you will want to experiment with several different ammo types, even within the same brand - air guns are quite ammo sensative. If you see a variety pack that piques your interest, buy it - the 25 or 50 rounds of each type might not seem like a lot, but it will be enough to tell you if it's worth buying more, or avoiding completely for your gun.