Addressing these in reverse order!
3/ Skill respec is relatively slow at the start of game. As you progress, the minimum skill level will increase and the speed of relevelling decreases (relative to your power level). By the time you get to end game, respeccing to a brand new skill is about 5-15 minutes.
2/ You can find some basic filters here which will help you get started: [0.9.2] Heavy'z Casual Loot Filters for all Classes v3.1
1/ Can you expand on this more?
I hope the above helps you enjoy the game more ahead of 1.0