Cisco :: Configuring 2960 For VoIP?

We just purchased cisco 2960 for our VoIP needs and we are using polycom phones, and Phone and Computer will use same port. Since Polycom phones are capable working with CDP protocol and we are hoping to get another switch to expand VoIP network. I found easiest way of setting up each port is as following (from the cisco tutorial)

Switch#configure terminal
Switch(config)#mls qos
Switch(config)#interface fastethernet 0/1
Switch(config-if)#mls qos trust cos
Switch(config-if)#switchport voice vlan dot1p
Switch(config-if)#switchport voice vlan 10
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 20
Switch(config-if)#exit

My first question,when we are using switchport voice vlan dot1p ,I thought we instruct the switch port to use 802.1P priority tagging for voice traffic and to use the default native VLAN (VLAN 0) to carry all traffic.Do I still need to create a Vlan 20 for data and Vlan 10 for voice ?

Secondly,same tutorial adds these commands as well,Do you think for our set up, using those commands are feasible ?

Switch(config-if)#switchport priority extend trust
Switch(config-if)#priority-queue out
Switch(config-if)#spanning-tree portfast
Switch(config-if)#spanning-tree bpduguard enable
Switch(config-if)#exit

Thirdly,when we get another switch and do the same configuration for the second switch, can I use any port on Switch 1 as uplink without doing any configuration ?