"If you want to hang out with someone, you want to carry a persona of that type..."
Not really. I never have the right persona, and I'm level 9 with everybody, in Naoto's dungeon.
Yeah, I never thought that was necessary. I was under the impression that what started relationships was not personas but how much of a certain stat such as courage you have.
Carrying persona's around certainly helps out during the social links you're working on (except for the first couple and the last rank ups I believe), but I wouldn't obsess over always getting them for absolutely every rank up. It is nearly impossible to 100% the social links without some sort of guide anyhow (to know the correct dialogue responses and scheduling). If it becomes a nuisance to keep pulling out persona's, I just wouldn't bother.
The stats (courage, intelligence) help start specific social links (most of the part-time jobs), but not the rank up process.
As for anything else, the only thing you might need a guide for are the endings, but not really if you just keep saving often enough. You can never screw yourself out of the true ending for good (thankfully).