I hear that all ports have a default vlan, usually 1. what happens when we set a port to access port 10? Does it still have a default vlan or just vlan 10?
The default VLAN is simply stating what VLAN all the ports will belong to in the switches default configuration. This is always VLAN for Cisco devices. In fact you cannot modify or delete VLAN 1. Changing the switchport access vlan x under the interface takes the access port out of the default VLAN and puts it into the defined VLAN.
The Native VLAN has to do with trunking (switchport trunk native vlan x), not with access ports. The Native VLAN is defined on a trunk and is used with protocols like Dot1q to define which VLAN will be untagged. Without this command, the default native VLAN is 1, which is also the default VLAN of the switch.