I suggest that you buy new boots, ideally last year's so that you get a discount. Go to the shop, try on lots of pairs. Very important to try the boots on first.
Buying last year's board/bindings will save on cost, or used stuff will also be fine for starting out.
Clash is probably a good choice, you sound like you're set on the park for most of your riding.
Don't skimp on boots, it's the most important part.