I'm not familiar with that sprocket brand, but that RK chain is what I've been using on my track bike. It's a good chain, one of the highest tensile strength 520 chains.
There will be no issues with the front sprocket without the rubber bushing, I've been using aftermarket sprockets for years. I've not noticed an increase in noise, but I wear earplugs every time I ride.
Performance will be the same. Just make sure you install in correctly. Unlike the stock rubber grommet ones, the aftermarket ones may have a raised "shoulder" around the middle on one side. That usually faces out, away from the bike. At least that's been my experience on my other bikes. Something to check and verify, as I'm not positive about the Versys. (I just got mine!). What's the stock chain/sprocket size on a Versys? Is it 520 pitch? If so, maybe there won't be a "shoulder" on the front sprocket. On my gsxr there is, but the stock chain is 525 and I changed to to 520. Perhaps the shoulder is to make up for using a narrower chain and sprocket.
As mentioned, the torque specs for install will be the same as the stock sprockets.
Changing gearing doesn't increase torque or horsepower. It changes how quickly the rpms increase, basically, which can result in increased acceleration.
On my track bike, I'll typically shorten the gearing by going down one tooth in the front and/or up 1-2 teeth in the rear. This results in the rpms being higher in any given gear. The result is quicker acceleration off the corners. It comes at the expense of top speed, as you'll reach redline quicker. On a streetbike, this change can make it seem buzzy on the highway, as the rpms are higher at any given speed than they would be with the stock gearing.
Conversely, making the gearing taller by adding a tooth to the front or decreasing teeth in the rear will drop the rpms in any given gear. The bike will feel less "peppy" on acceleration, but for a street bike, it'll be less buzzy on the highway, as the rpms won't go as high.
A lot of it is personal preference. For example, most folks like -1 front, +2 rear on the gsxr for the track. I don't, I prefer -1 front 0 rear. The +2 changed my shift points, I had to shift sooner, and in places on the track not convenient for me.
Hope some of this helps!