From what I've heard, MP games are usually decided before diplomatic affects from envoys have a chance to kick in much. Feeding, however (giving credits and resources to allies who need it) is essential. The same basic strategies from Entrenchment are used: combat is basically the same. Expand quickly, upgrade and fill out your fleet supply when expecting a battle in the near future, and know the counters for each unit. (every ship type is weak against some other ship types: knowing the numbers well is essential if you want to be a decent MP player).
ICO is most active in the late afternoons and evenings, US time.
