Depending on how involved and motivated your OSO and OSO team is, they'll help you get in shape, but you're going to have to put in the work. You also don't want to show up to OCS performing at the bare minimum. When I say you need to be in the best shape of your life, I mean that.
Age waivers are given pretty readily it seems.. that doesn't mean you'll get one, but it's not impossible.
In the meantime, your best bet is to rock the ASTB. There's plenty of ASTB gouge and books and info out on the internet and on this site (use the search function). If you max the ASTB or get high scores, it's hard for selection boards to ignore that.
For rec letters, I'd say it's better to get them from people that actually know you. I'm sure people on here would disagree, but I never felt comfortable seeking out individuals that maybe had the rank or title but didn't know me or worked with me at all.
Also, I want to add some clarity for your timeline just because you are a bit older. You'll go to OCS (10 weeks) and then TBS (6 months). You'll then show up to Pensacola and wait god knows how long to even start NIFE (I had a 7 month wait) I did API, I'm not sure how long the new NIFE program is taking (I'm assuming a couple months). After that you'll have 3-7 months before primary (primary took me 6 months to get through....other guys it took 10 months)...then you have another 2 month wait until you start advanced. helos took 10 months to get through. jets are taking anywhere from 10-16 months).. then you have the FRS..6-8 months for helos and 12-18 for jets. THEN you hit the fleet. It's ridiculous, but that's just the reality right now. Something to think about. There's nothing wrong with looking at your options in different branches as well.