Here are my thoughts on the options you presented. I have less experience on the track than you and also don't have any of the mods you are suggesting, so my advice may not be worth much but here it is anyway.
1.) Non-compliance beams and links - I don't know much about this mod but in your own words it seems like it might not be the top priority at this point.
2.) KW suspension - Would be a nice upgrade, but how dramatic an improvement do you expect over the stock suspension? I would consider this a nice to have... I don't think the stock suspension is a real limiting factor to you at the track right now. I could be wrong.
3.) Brake ducts and piping - Would improve your pad life and maybe improve your braking performance for a fairly small investment. Seems like a good low cost option to me.
4.) HANS/Harness Bar - You are basically making a tradeoff here... improved safety in the event of a serious, non-rollover crash versus possibly compromising your safety in the event of a rollover. I believe the odds are much more likely that you will have a non-rollover impact, especially when you keep in mind that only a small percentage of rollovers could cause an issue with the harness bar and a rollover that serious may be a problem even if you don't have the harness bar. I think you also have to do seats with this mod.
5.) Driving Suit - Seriously? Given the expense and the minimal safety benefits, this would be at or near the bottom of my list of priorities.
6.) Tracktime, Tires, and Pads - You're going to spend this money either way. This is probably coming off the top of available track money.
If it were my money, I would first spend it on tracktime, tires, and pads, up to a certain point. It would be foolish to track the car 20 days a year, spending thousands, without dialing that expense back and putting that money towards safety gear. The brake ducts are a cheap mod and no reason not to do that as far as I can tell. If you have the money, then I would go for the harness bar, HANS, and seats as my next option.
My 2c, others may have better advice for you.
