Well, figures that 5 min after posting this, I make some progress... imagine my surprise when googling "man udhcoc" provided answers!

"dhclient tap0"
can be replaced on the 770 with
"udhcpc -fnq -i tap0"

(f = foreground / don't fork, n = do it now, or exit/fail, q = quit after getting a dhcp reply)

It looks like I should be able to tweak the settings to just run constantly and monitor tap0.

Anyway, after running that command manually, my route table is now correct. I get "default" traffic routed to "192.168.1.1" which is indeed my openvpn gateway.

I still don't get a proper nameserver setup, like I do on my regular desktop...
/etc/resolv.conf points to 127.0.0.1
and
/tmp/resolv.conf.wlan0 points to my 'old' (non-openvpn) nameserver
and no other /tmp/resolv.conf.* exists (wouldnt it have been awesome if a resolv.conf.tap0 was created pointing to 192.168.1.1!)

So now figuring out the nameserver is the last piece of the puzzle...