My friend owns and operates a small ISP that serves a small town and the
surrounding rural area.

His current setup is wireless routers in bridge mode. As a first step, I'd
like to move him to an OSPF routed network. I've never built an OSPF
network, can you guys please recommend a good page for reading up about it?

I'd like for the majority of the routers to be running cerowrt, however
that would require at a minimum external antenna connectors. I understand
that the only hardware supported by cerowrt (so far) is the Netgear
WNDR3700v2. Is it (reasonably) possible to attach external antennas to
these routers?

Finally, I'm wondering how much interest there would be in some form of
access to this network for the purposes of analyzing or proving concept
code.

Sincerely
Andrew