Do i have to keep my wallet online for the masternode? Sorry if it was answered already, i didn't find it. Thanks!
Yes. Your wallet needs to be setup and ran as a master node and it needs to be online to be part of the network and to receive it's reward for doing it's share of the work.
Thats actually incorrect, once set up properly in a controller wallet / remote vps configuration, you can safely take your coins offline, yet the coins will still be sent to your wallet while offline.