Hi
-What Matt explained is true, 802.1p is a layer 2 protocol which never crosses wan links, shifting prioritis to DSCP mean Layer3 and then can be done over WAN link.
- "Does tagged vlan require the vlan to be configured on the server nic drivers, if they only are member of one vlan?"
Why you need to Tagg the Server link and you only have one Vlan.
Just keep the Ports connected to Pcs or Server Untagged (unless your server's NIC is 802.1q compliance and you need this solution).
- "I guess I have to enable 802.1q on all ports that are uplink to other switches and the firewall."
Thats true, Uplinks should be Tagged all the way between the Switches to Carry All Vlan traffic (except the Default_vlan which is 1 by default should be untagged).
- "how do I make sure a specific server/client ect. only is allowed in a specific vlan?"
Would you explain please :)
- "Im affraid when configuring my switche,I will cut my self off."
You will, Cisco's default protocol is ISL, you should configure the Standard IEEE 802.1q before Tagging the Port to a ProCurve switch.
And, be sure that the Native Vlan on Cisco switch (by default 1) is same as Default_Vlan on ProCurve switch (default to 1) and both untagged (or access port not trunk on Cisco).
Good Luck !!!