I'm not sure what the theme league rules are, but I agree that you've spent too much money on PAs and IP for players that likely won't be playing much, especially if there is AAA. Since you said you don't know how AAA works, the site will randomly select players from history for your team, assign them fake names, and they will make up your AAA. So you're probably going to get some help for extra PAs and IP from these selections.
I would focus on the absolute best starting 8 hitters I could pick (using AVG#, OPS#, and whatever stats fit your park (1B/100# or 2B/100# etc), the best SPs and 3-5 bullpen guys (using WHIP#, OAV#, ERC# and HR/9#) that I could find. If you have extra cash, you can sink it into a good PH or an extra pitcher. I typically like 900-1000 quality SP innings and 300-400 quality RP innings and then fill the other 100-200 IP with the AAA guys.