I have but not from seed, I just replanted them from the garden centre pots into large pots with other herbs and they have continued to grow just fine.
Yep. I've got a pot in the garden that has parsley in it. It started growing again from last year's plant. Easy to grow, just put it in soil and water regularly
You can buy them in pots in Waitrose, and I guess in other supermarkets too, for around £1.40 a pot.
I prefer the flat leaf variety. (more than just a garnish)
Bring the pot/s in at night, until they've acclimatized otherwise a sunny kitchen windowsill for convenience.