Ski length:
my skis are 182 and im 179cm maybe 180cm this year :-) but basically dont let ski length drop under your nose, skis at around eyebrow/forehead is pretty solid choice, too short skis make you look kinda foolishh, ofc u might feel more agile but ye.. few centimetres down from your own length and you're fine.
Bindigs:
since you are just getting into skiing, you dont necessarily need anything superb, any normal ski binding will do.. just dont buy the first cheapest one, they just break. maybe buy set of skis with bindings in them?
shouldnt be too bad.
Boots:
u go in some store where you can test them it would be good, salomon SPK's works very well, or some cheap fulltilts like the drop kicks/booter. (i have booter and lightest, and comfiest boots i have ever own)
but basically any boot is just fine. sizes vary between makers, dalbello and full tilts have quite big size difference between each other so it would be nice for u to test boots first so u dont end up buying too big/too small. but its not that far away from your everyday boot u use for walking and sht.. maybe buy little bigger so u can fill more warm socks in them and stay nice and warm in slopes..
Helmet:
Yes.
what skis to buy?: again, you're starting and its not that big deal, i dont know how old/tall you are but armada codas were my favourite when i was 13.. line afterbang.. and really cheap and really good ski atomic infamous. just about any ski will do just fine..
and then just go ski.