Use the Airdrop network to access a computer? I'm using airdrop to transfer files and stuff to another macbook. Looking at the output of ifconfig, I can see that airdrop creates a VNIC to communicate with the other computer. 

Is there a way I can use that connection as a full fledged AdHoc network connection, i.e ping the other computer, use normal file sharing etc.? 

Because even though I can use airdrop while being connected to another wifi network (i.e the network card can connect to an adhoc connection as well as an infrastructure connection simultaneously), if I use an adhoc network through the wifi icon in the top bar, I am disconnected from the other wifi connection.
Yes, the VNIC created when an AirDrop window is open can be used by any application. AirDrop simply runs Bonjour (mDNS/DNS-SD) on that interface to discover peer and the TLS to transfer files. Any network application that can be configured to use a specific interface and supports IPv6 should work.

For example, pinging (replace X with whatever the interface number is in use, see ifconfig for example): ping6 -I p2pX ff02::1