Some of these question/answers are from the OLSRd site.
Yes. It even has implemented some of the extra functionality mentioned in the RFC. See the RFC Compliance section for complete list.
Yes. But keep in mind that they intentionally were not designed to be used at the same time. The network topology can be quite "messy" if you start using these two.
You probably don't have the GTK2.0 development libraries installed.
When a new gateway is detected, the Mobile Node checks the distance (number of hops) to this newly discovered gateway compared to the current gateway. If there is a shorter distance, this new gateway becomes the current (default) gateway. See section 12.6.2 in the OLSR RFC (RFC3626)
Most of the time this is a configuration error: Check the following:
If using WLAN interfaces make sure the ESSID/key match.
Make sure the cards are set in "ad-hoc" mode and not "managed".
Make sure you are not blocking UDP/698. If using netfilter run ip6tables -L as root to see what rules are set. ip6tables -F flushes all rules.