Unless the sleeping bag is a typo I would say YES you need something better. If the temp is looking to be -15 to -25 and you only have a -5 sleeping bag. You're heading for big trouble. Ya gonna freeze your bippy off.

As for bike parts freezing. I've never had it happened. I would say it will depend on how much snow you have falling while your out. The wetter the conditions, even snow melting on the roads the better your chances of something freezing over. Look at the bike each night and see if you have any kind real build up of salt/sand/snow on the bike. Knock/wipe it off and keep the bike clean. That helps more than anything else. If nothing is covered with salt/sand, it gets kinda hard for anything to freeze.

The past two days I've ridden around 80 miles each day, unloaded. That's with average 50 feet of climbing per mile. It all depends on how good of shape you are. I've ridden 130+ miles on the first day of winter a few years back here in New Hampshire...again unloaded. It all comes down to your fitness level.

While winter backpacking I've just used snow for water...not much else you can use. If you are going through towns you can fill up there otherwise you have to rely on snow. Should be plenty of it up your way.