I'd get the cheesy vinyl coated steel traps that cost about $20 ea. That way when they get stolen (if you crab much they will),you won't be out a ton of money.

The cheesy pots work as good as anything out there. I've never lost a pot to the tides,but I'm sure to use enough rope so the float won't pull them off the bottom. If you're concerned about the tides,you can add a few pounds of rebar in the bottom to weigh it down.

IMO the best time to crab is when its open. These days you really can't be picky about when you're going or the WDFW will close the season before you can go. I've never found that one time of the year is better than the next anyways. I limit when its open in the Summer and I limit when its open right now.