1. As hovis said, under the pillion seat there should be a hook that you can put your helmet D buckle in & secure the pillion seat/cowl back on. Just close the visor to keep the rain out.
2. You say you don't want a box, but it sounds like the best solution. A bike is fine for commuting to one place of work when you can store your work clothes in a locker but going to different places is harder. Ask Bluepete about securing a box to the pillion seat if you'd prefer that?
Could also consider a bike cover, just leave all your bike gear on the bike & put a bike cover over the lot?
a) Sounds like you've got a half. Surprised Hovis didn't jump at the chance of pic whoring his old fully faired
b) yup it's a Girls bike
I mean Sports Tourer