Aye, I don't see the problem with limited intra-realm combat. This isn't something that would happen constantly, nor rampantly, and could be tightly controlled with specific triggers and conditions. I also like the limited amount of permanent or semi-permanent friends/enemies. I'd say a maximum of 3-5 enemies and 3-5 friends is the most you'd need. I mean, !@#$, it'd make you think twice about declaring fealty or bloodfeud unless its seriously necessary and important both mechanically and RP-wise, rather than being a feature to be abused. I think 2-3 of each at semi-permanence to account for the fact that a declaration of friendship or bloodfeud would take a long time to 'remove from the system' due to the long-standing and widespread feelings involved in multiple members of the family both player and NPC, which would once again reinforce a more serious mechanic where being sloppy with your friends and enemies will only screw yourself over.