Do the springs first after your bike protection bits. I started with Hyperpros on both ends. A good bang for the buck, but I would go with a .60kg Bitubo spring on the front and a Hyperpro on the rear.
Stock is .46kg front. Hyperpros are .52-74kg. The bike alone will compress the lighter coils together and you will be riding on the heavier section of the spring. I never came close to using all the travel I had, which is kind of the point of it all.
I had the .60kg spring with my Bitubo cartridge and found it too harsh, but the cartridge is pressurized adding to the effective weight of the spring. Should be about right on a stock cartridge. The spring is longer than stock, so you should remove the spacer. If you bottom it, you can add a shorter spacer.
The real culprit on the forks is the valving, it has the equivalent of hydro locking under fast fork compression.
My Bitubo works well with a .55kg Ohlins, but it requires special equipment to revalve or service.
The Hyper pro rear spring is OK on the shock. Mine has gotten better with age as shock wear has decreased it spiking and rebound is still good.
To deal with the abrupt throttle I went with both a fuel module and a G2 throttle tube. The real culprit is lean low rpm fueling cycling quickly into a richer mixture at higher rpm. If your off road keeps you in the 2,200 rpm range or higher you may not notice it or at least can control it. It is a band aid fix, but made plonking along possible.
I have a Scott's stabilizer. It can save your butt is sand or silt. The front goes into and out of ruts easily. Gives the bike a heavier/stable feeling on pavement.
It was the last mod I added. I would love to hear from the last poster I recommended that advice. He ignored it.
As for tires, I have run a bunch of them. In summer hard pack with a little gravel the non knobbys are adequate. Gone through several sets of TKC as a general purpose tire. Currently a Pirelli knobby on the rear. I am not expert enough to feel any real favorites.