Reactor Extreme Sleeping Bag Liner

No - to keep weight and packed volume down, we did not include a side zipper. Snaps at the shoulders mean a wider opening than some liners for entry and exit (and the drawcord footbox allows you to vent your feet or hitch up the liner and walk around camp)

Yes. It can be washed in a machine with normal supermarket detergent - but avoid fabric softeners which reduce wicking performance. Machine dry on a cool/low setting (no dryer sheets) or air dry

This depends on how well your sleeping bag retains warmth (not the same as its temperature rating), how well your pad insulates (not the same as its R-Value) and a lot of other factors. You should see a fairly solid boost if the liner is used with an appropriate sleeping bag and pad.