Sorry, I took longer than NormanB or Duster to finish the post, so you'll see some duplication here.
I don't have the older model 400, but I really wonder if you need all those parts. Can you post some pictures of your existing parts that need replacing? One that would be very revealing, is if you can put a straight edge against the face of the variator you want to replace. If you have problems with posting those, just PM me and we can work it out.
Your profile shows you have 27 miles. Is that missing a few digits?
I took the advice of a vendor who used to be on here a couple years ago and ordered all the parts you have listed. When I got to about 29,000 miles and put the new variator pulleys in...and noticed no difference. I took them back out and left the originals in till I sold the bike at 49,000 miles. Any "groove" that had been there, wore off as the belt moved over the ridge till it was smooth.
You could buy Malossi parts. They are good...but more money. I doubt they'll give you that much more "bang for the buck". A better investment would be to buy the 18 gram Dr Pulley Sliding weights.
Regarding the clutch spring compressor...it's not needed. Take a look at Mitch's (micbergsma) video on replacing the clutch. It is for the 2007+ model, but it shows a couple still pictures of me holding the clutch down as I thread the nut on to the driven pulley. That huge looking spring isn't hard to hold down with your feet. Just make sure you put something on the floor under it so you don't mar the driven pulley on the bottom surface.
One note...I tried to take a short cut, thinking it would make no difference...and almost ruined a pricey part. I started the threads by hand, then instead of tightening the nut the rest of the way, I just used the impact wrench on it. I'd advise tightening it as far as you can by hand, then with a socket wrench. Then use an impact wrench if that's the way you're doing the final "torque". Also, you might want to look at the rest of Mitch's video. While it is for a 2007, it will be very helpful for ideas as you do the same on your 2004. Mitch also did some videos for the earlier model 400 and might have one specifically for yours.