welcome to the sport!
thats probably not the setup i would have recommended you start with for both you and your step son, but never mind, as long as it works, you should have a great time. this is not the time in your paintball career to be bogged down in all the sillyness is that in paintball gear lets just get busy to having fun
tips:
1. buy a good mask. go to a paintball shop, and try them all on, and regardless of price, buy the one you like the most. its the most essential part of your gear, and it keeping you comfortable and fog free is step 1 to having fun in paintball. its impossible to have fun with a mask that you hate. don;t worry, a mask will last 2 or 3 years, and the lenses are replaceable, so you will get your monies worth.
in your case, your next step is going to be a loader. a nice, fast, simple, reliable loader. rotors are gosh darn expensive, and i don't think they are worth it. nice loader and all, but way way to much money. a nice halo too, or even the vmaxx might be what you want instead.
then ... go and have a good time!
"because every vengeful cop with a lesbian daughter, is having a bad day, and looking for someone to blame"