I would say now that you have bought the kit, have a go with it. If you start looking around at all the things you could buy you could spend a fortune and end up with a lot of stuff your rarely use, depending on what you find you like doing.
If you get stuck on anything in the kit there are tutorials on pretty much everything you could ever need on youtube. I suggest 'very pink knits' - she has really clear tutes on all sorts and does some of them in slow motion so you can watch and work along at snail's pace till you get it.
I woudn't go out and try to learn every technique and buy every bit of kit on the off-chance. If you find something you want to knit you will find all the advice you need to help you work out how what you need and how to do it.
One person's favourite method is another's never again etc. I love magic loop, but some people would much rather use dpns, I much prefer top down socks, while others prefer toe up. I prefer knitting most things on circs and in one piece, except intarsia, but most things can be made by lots of different methods. And sorry if that's just chucking in a load of mystery terms, the point is there are loads of techniques out there and loads of different ways to do things. I would say just have a go and you will find your own favourite way of doing things. I'm sure there's lots of people on here can give you pointers if you get stuck on anything.