Doing the CRift does nothing with your char. You play a completely different char. So you'll still be level 1 when you go ingame and collect your cache. Might want to check this out or just play the current CRift for this week to get a feel for it, if your haven't done any yet.
Oh, good lord. Of course. Lol. *stands in the corner*
Of course, you won't be level 1 anymore once a new toon does a challenge rift at the beginning of the season and cashes in to get the Blood Shards to gamble. But, I am assuming you'd still be pretty low (under level 10?).
For the few Challenge rifts I have completed they have always been solo attempts -- I have never been in a group. And my standard operating procedure for my little clan at the outset of a season is to always do bounties and rifts. I suppose the 4 of us could all do one Challenge rift before doing anything else. That would be easier, yes?