dude, if this is really ur first time for all those things, awesome job! That rocks. Seriously.
You guys defenitely got potential. My opinion would be to take the recorded tracks to a pro mix engineer if your budget allows and then to a pro master house. If not, try the pro master house at least. I think Disc Makers can master it for a couple hundred bucks. They did Newsted's album and some other stuff.
If there is no more budget, I would try to get better at mixing. Sounds killer already. But song needs more dynamics. Like, more build up, quieter versuses, then explode your choruses and big parts, ya know? Make em in my face so I can rock out. I'm talking about the mix stage here. Automate your faders. Ride the vocals, the guitars, what not, record your passes, be patient, save backups, etc.
My only complaint on the mix is the vocals: is this the desired sound you had in mind for vocals? Cuz it seems like at the vocals, you sort of got lost as to what to do with them. They sound a little stuffy and just kind of annoying. I thought I heard a delay in there. Maybe try a reverb, or 2 tracks, EQ'd to seperate frequency ranges for thickness. Perhaps a hint of chorus. I'd play with the vocals a bit more. Maybe give them a little more leveling with the compressor. But defenitely, whatever you do, at least take an EQ and cut around 500-600 Hz and open those vocals up so they sound a little more breathable and open. Sounds like they competing with a few other frequencies in the mix or something.
Mastering: unless you have a $10,000 acoustically tuned room or free access to one, save up some money and send it to Disc Makers. You've got a nice product: don't sell yourself short by skimping on the biggest aspect, which is the mastering. Trust me. You won't regret it.