Yeah, I couldn't remember how far the Shana movie covered exactly, but I knew it covered Shana and Yuuji's meeting and the first villain.
You should still watch s2 just to prepare you for s3, which is really good. Plus, it's the finale, and you'll probably want closure to the story. s2 isn't as bad as what I made it seem like. lol
When it comes to Shana openings, I like Hishoku no Sora quite a bit, but my favorite would have to be either Joint from SnS s2 or Light My Fire from s3.
Out of all the KugiRie characters, my personal opinion is that Aria is the worst. I love her design, but unfortunately she got stuck with a crappy author for her series. I read the light novels and they were pretty bad lol
Also just my personal opinion, but I don't count Nagi as one of Rie's "tsun" roles because Nagi isn't overtly tsundere except at the very beginning.