ARP is delivered to WiFi Station?

Today I monitored with tcpdump the traffic on the ethernet- and wifi-interface. I was not sure, if the AP mac address is somehow used in the ethernet frames. Answer is no(?).

I was a bit confused, after seeing that ARP messages are actually replied by the client device?! I always thought the AP is answering?
Actually I'm flooding my WiFi network with useless information that could be stored in the AP? So every layer 2 broadcast, DHCP discover, ARP, ..., frame is really delivered in the WiFi domain?

Edit:
The ARP message was not a broadcast, instead a unicast transmission was happening.