An arrest warrant for unpaid parking tickets means nothing. Never heard of anybody being arrested for that though. Government usually denies licence renewals etc until you pay, but it won't affect a PAL application. Has to be parking with violence in the past 3 years to matter. However, the fine will go up if you don't pay the tax. Read this. Add the W's. .thelawcentre.ca/defending_traffic_tickets
The meds quite likely will at least delay your application. Paxil is used to treat depression, obsessive-compulsive disorder and anxiety. That'll send up huge flags. A letter from your MD might help.