1. Well, basically yes. But I know some Sony DV camcorders allow you to record stills on the cassette as well. Confusing, right? Anyway the picture quality of the stills on cassette is poor, and hence you can just ignore this feature.
2. You can't record video to a mini-DV cassette on Mpeg formats (again some Sonys allow you to shoot mpeg 1 videos on cassette; just ignore this if you find it confusing). Instead it uses DV format which has a better picture quality and lower compression than those of Mpeg 2 format. DV is recorded at 1:1 time ratio. So a 60-minute cassette will allow you to record up to 60 minutes of video in SP mode (90 minutes in LP mode).