1. We cant trade on season, in any way shape or form.
2. Non-seasonal, while gear is dropped per user/player, you can trade/drop/gift (via mailbox in game) with other players
3. Your best bet would be to purchase (or find people to run) some Key Rifts and then Greater rifts and have somebody carry you through higher difficulties so you can obtain gear fairly quickly.
4. Shoot me a PM I can help you.