Tried it out.

0 sats transaction fee from my node to theirs (2 hops) on a 1000 sat (minimum amount one can deposit) and a 10000 sat invoice. Tried from my Zebedee wallet first, but failed for some undefined reason (liquidity issue? zebedee policy? can't say at this point).

1000 sats (~0.5 dollar) transaction fee to withdraw 10000 sats (minimum amount one can withdraw) from Kraken to my node again. I think this fee is fixed.

Max deposit is 0.1 Bitcoin.

EDIT: Withdrawal was pending, and failed just now. No useful information other than a "bad request" error.