You take all your kit with you every time you go on draft and you will get kit musters in Phase 2, and the lockers are bigger, but not much.
Where civvy clothing is concerned, if you can't carry it, don't take it. When I was a Phase 2 DO I lost count of how many came to see me complaining they had too much gear to carry and expecting pusser to pay for it to be sent on, they either had to ditch it (not issued kit) or sort it themselves.
Just a word of advice which you can ignore if you wish.