Don’t think that hub is going to be upgradeable. Getting a front wheel with Hope ProII hub is a good upgrade as that can be converted to any standard. Hope Hoop front wheels come a little over a £100 and should come with QR and 15mm converters.
For XC/Trail forks most, if not all, are 15mm now.
Which fork depends on whether you’re looking to lose some weight…if this is the case maybe 120mm Rebas. If you’re looking for longer travel, Sektors or Revs are excellent although you might need to bring the travel down from 150mm…reckon dual postion Sektors (120-150) would be fun. I had a 2009 EX8 and put Fox Talas forks on it…on the fly travel adjust between 100, 120 and 140: it worked very well