I'm going to go against the grain here... Only buy that expensive tripod if you're actually going to use it - I'm sure 95% of all tripods sold get used less than 5 days a year! I'm certainly guilty of leaving mine at home or in the car most of the time and it was expensive enough that I could have bought a nice new lens instead. Or a couple of weekends taking photos in new and interesting places. Remember all the money you spend on camera gear is money you could spend on photography instead.
Luminous Landscape is the best site I've found for informative articles - technical and aesthetic - and their forums are good too.
This list is also quite useful reading material.
There's a debate about this (see elsewhere on this forum!) but I think for landscape stuff you want to be shooting in raw all the time. You can get the highest quality image that way, and you get more control over how it looks.
In terms of lenses, an ultrawide like a DA15 or Sigma 10-20 gives you an amazing new perspective and a lightweight tele zoom you get distant detail and opportunistic shots of wildlife in good light. Price was an issue for me so I started with a used Tamron 70-300 from Ebay, these days the Pentax DA-L 55-300 is a good bet too (optically the same as the more expensive version, just buy a lens hood for it).
There's also a whole world of interesting old lenses, some of which are cheap. And a small number of FA Limited primes which are definitely not cheap, but inspire a sort of religious fervour. The lens database on this site is excellent.