bridge interface under wlan and eth

Question

I have the following topology:

I have a laptop with a WiFi NIC and a docking station with an Ethernet NIC. Both network connections are connected to the same LAN. What I want to do is to use the Ethernet port as much as possible, and, when I decouple the laptop from the docking station, I want it to switch to the wireless NIC. I want all this without my services being affected/going down => I must have the same layer 3 address running all time and the WiFi NIC must always be connected to the wireless network, although no bandwidth is used.

I have thought of a solution (I'm using Linux):

1. Disable DHCP on wlan0 and eth0.
2. Add these interfaces in a bridge.
3. Activate a DHCP client on the bridge interface.
4. Make sure the bridge interface has the mac address of wlan0 so it can communicate properly on a secure WiFi network as well.

Some restrictions and concerns:

1. Both physical networks are connected to a switch on ports which are set as vlan access port type. And I do not have any control over that switch.
2. I do not know the DHCP protocol by heart. Do I risk wlan0 interpreting the DHCP response instead of the br0 interface?
3. How do I prioritize br0 to use eth0 when it is active and consider wlan0 in a sort of a logical down status, without braking the wlan0 wifi connectivity?