Is anything before Age of Destruction playable? Are old uniques playable; vehicle or mech?

All sets are playable with no restrictions. The earlier set retirment was done away with on the opening day of origins.

This does not mean that you can put pilots and gear on pre AoD Mechs. but you can play them and they generally are cheaper to field.

Yep, anything goes. You can field an AgroMech MOD and a Nova Cat in the same army, for example. However, keep in mind that some tournament events have specific rules. When it comes to casual, non-tournament play, there never have been any restrictions, of course.

So basicly everything is playable except you cant put pilots or gear in older mechs?

Your understanding of this intricate matter is correct.

lol ok cool thanks alot for the help guys!