SS brake lines do very little on their own, you should upgrade from OEM pads and also an aftermarket master cylinder to really gain the most out of your braking components.
Rearsets help with foot positioning which in returns helps you to be more comfortable on the bike.
Levers and windscreens are not really something I would recommend, it is a waste of money and offer no real gain.
As far as rad guards go, check out COX rad guards, if they make one for your bike, buy it. If you find it too expensive, you can always get some chicken wire (or similar) from Home depot and fabricate your own.
Also, there is no sense in doing all these mods in the winter. Yes you can take your time but then you have to wait forever to enjoy them. If you can afford it, do it now! You won't regret it.