Variable filter that handles the ND2-ND400 (1-9 Stops) range, a ND1000 (10 stop) filter and a CPL should be all you need.

Graduated filter can be done in post so no real need for it.

The Nano-X series is good value for money.

Don’t take people who talk about color casts too seriously, there can be a color cast but it’s easily fixable in post.

Also when you are buying from K&F be sure to check out their other sites as well, most big markets have their own top-level domain with everyone having different prices and sales. Just yesterday I ordered a Black Mist filter from their .com site that was half the price from my local top-level domain. And vice versa a couple months ago, my local site had half price compared to their .com domain.