Looks like those are good options for grips and bar ends. The current handlebar, being one with some "sweep", may warrant replacement with a more typical mountain bike "flat" bar, cut to your preferred width. You'll need to ensure the clamp diameter (where the bars mount to the stem) is correct for the stem.
I think doc's comment comes from the first generation belt system, where snow could pack up in the rear cog. I rode mine year round and never had this happen, as have many others with no issues. A few folks encountered the issue, but it is not as bad as doc implies. It is similar to someone saying "don't buy a carbon fiber frame because it will break". Just because some people had an issue does not mean you will.
In fact, I found the belt system to be BETTER in snowy conditions than a chain for numerous reasons.
Regardless, this has been rectified with a new rear cog design, and the snow thing is not an issue with centertrac. You can tell if you have centertrac by looking at the belt itself. If the teeth are solid all the way across, you do not have centertrac. If the teeth have a groove running down the center, then you have centertrac. Here's a pic of a centertrac belt:
The final thing I'd mention is that
if you have the original drive system (1st generation), the original rear cog was made of aluminum, and can (will) strip at the interface with the hub. Gates will send you a new steel cog free of charge. Simply send Gates an e-mail and request a replacement free of charge. You or your LBS can swap the cogs in less than 30 minutes, and you are set to go, with two issues solved (snow packing and the weak cog).