If the Ak you're referring to is an Aftermath Kraken, then yeah that's an ok gun for the price, but if you can afford another hundred or two then you could get something much better. Spring pistols are pretty much useless so I wouldn't bother. Most sidearms are gas or electric powered and the cheapest are usually at least $150. Sidearms aren't really necessary so if you're on a budget then hold off. On the note of that Kraken, get a better hicap (or better yet some low or realcaps) as the one that it comes with is garbage. Also, get a better charger, the wall charger that it comes with will kill the battery. Also, get some good ammo, bad ammo will mess up your gun. BB Bastard
bb's are very good, he also sells a good smart charger for a decent price. Some surplus camo wouldn't go astray either, if you don't already have any from paintball. That's all you really need.
As for fields and events around you, you should check out the ON area of the events section
. There's plenty listed there, provided you're 18 years of age or older. If you're not that old then some few places will allow 16+ but ask in advance.