Downloading torrent movies onto MacBook Air

If you are referring to sites that offer pirated commercial movies and music, it is better not to go to such sites at all.

You can get a subscription to Apple Music or Amazon Music that offers you ad-free access to just about anything in a huge music catalog for only $11/month. If you're a music fan, that's a real deal – less than a CD used to cost, and only about 1/2 to 1/3 what the record companies are trying to charge for a single vinyl album now. Plus, it is above-board, and you don't have to worry about scammers or malware.

I'm not about to get rid of my CD collection, and am still adding to it, but I jumped on that.

There isn't anything as good as that for movies, but it's still better to buy or rent them legitimately.

no, plain mp3 and mp4 files cant infect your system. however, if you download music/movies, never open any executable files that come with it. as long as you're relatively computer literate, it'll be fine. youtube music with adblock works fine if you want to stream music for free in a legal way. movie websites are blocked all the time and the legal way is to ask your mate for their account