Yep, quarantine for at least two weeks - longer if the fish shows ANY signs of illness.
No medication, I try and avoid medication if I can. Partly because I need a script from a vet for everything where I am but mostly because I believe clean water, low stress and good food will fix most problems. So far I haven't had a problem doing this.
Water changes vary depending on where the fish came from, fish size to tank size ratio, if the fish appears ill etc. Decent (50% or more) water changes at least every three days (usually every second day but sometimes I get lazy) larger and/or more frequent changes for fish from bad stores/rescues.
So far so good.