2. Aya has been calling (record store) Mitsuki 'Onii-san' for a few chapters now, which I've tried to translate in a bunch of increasingly awkward ways, but I've given up and will just use 'Onii-san' from now on.
3. Sorry for any confusion, but I assume that 99% of you know what it means anyways (for those that don't, it can mean any of dude, bro, guy, mister, etc).