Hello Thomas
It really depends on what you mean. Do you want to be able to run the OSPF routing protocol over a network topology where IPSec is implemented? This can be using DMVPN, GRE, or simply using a pure IPSec VPN. But there are some additional tweaking that you must do for it to work as by default, OSPF will not function over an IPSec link. Take a look at the following post for more details:
In addition, take a look at the following lessons that include situations where OSPF is being run across links where IPSec is employed:
Yes, you could do that, because in essence, a DMVPN is a multipoint GRE tunnel, and GRE supports multicast, thus it supports OSPF. A pure IPSec tunnel such as that described in the following lesson would not function (as described in the post above.)
I hope this has been helpful!
Laz