SLs count as installment loans, so they don't affect utilization, but they do count for payment history and credit mix. If these are your first TLs and/or installment loans, you should see an increase in scores along with any slight decreases related to inquiries and having the new accounts, but those dings should be pretty small. I also get a small ding according to MyFico for having my installment loan balance so close to its highest total, but for reference, my file had one 6 year CC, 2 open (deferred) and 4 closed SLs, and 8 months of an auto loan, no lates and was around 750, so it wasn't holding me back.
Having the loans in deferment does zilch for your score either way as far as I can tell. Although it'll usually say "deferred" under the notes for the account, mine have always been listed as "pays as agreed" and therefore count toward my positive payment history. A manual review of your account will show that "deferred" status, but when you explain that you're still in school (and not putting them into deferment because of financial hardship for instance), I don't think that will have any negative effect.
If you don't have any CCs, opening one should improve your credit mix and boost your score, if you do have CCs, you can pop over to the CC forum to learn how to use the balances and utilization to squeeze some more points out before you apply.
Good luck!
