You'll need to leave your rhubarb alone this year if you have divided and replanted. Don't remove the thin stems, they are helping to feed the roots.

Yes, leave it alone but feed it well - rhubarb responds well to rotted farmyard manure if you can get it. When it grows more vigorously next year try to remove only one stalk from each centre, otherwise you will weaken the plant until it is well established again.

Steragram is right well rotted farmyard manure or horse manure works wonders for rhubarb... I forgot that bit lol!

I'd risk removing a few stems from each crown next year.

Yes, but not all at once!

I never remove all the stems from my rhubarb, as said above, the stems are there to feed the crown.