I'm about to start syncing node on the server, do you know if there are any requirements to the server, like CPU or GPU and most of all, free disk space.
Any tips about syncing on server?
EDIT: NOT TO MINING PURPOSES.
The full blockchain is over 200GB. So long as you have even a relatively modest desktop CPU (or single core of one in a virtualized cloud environment), you should have no difficulty staying in sync, CPU-wise with the blockchain (at least until sharding comes around). go-ethereum is happy with a few gigabytes of RAM (I haven't used it in nearly a year, but it was quite happy on an Ubuntu VM with 4 GiB of RAM until the state-bloat attack.
The blockchain can currently grow at a maximum of about 100KB/block with the current gas limit; assuming a block time of 15s after the ice age is... frozen, that's another half a gigabyte per day. So, to be safe (but without accounting for possible growth due to sharding), set aside about 200GB/year you want to keep your server running in addition to the existing 200GB. You'll want/need this to be on an SSD to stay in sync. Your OS' size is relatively negligible to this.
There is no need for a GPU.