Can I withdraw my deposit anytime I want?
You need 0.01BTC to withdraw and I think $1 with other currencies.
^ What Mixevil said. As long as you meet the minimum withdrawal criteria, you can withdraw as often as you want. There are no withdrawal time limits.
I deposited today and it says "available for withdrawal": 0.1
but if I click withdraw I just get a message with a lower hardcoded amount and a message: "The amount is smaller than the minimal amount allowed"
There must be some limits then right?
I was confused by this at first too. The 0.1 you're seeing is in USD, not BTC. You need to wait until you get the USD equivilent of 0.01 BTC to withdraw.