Try to arrange to do kingdom book keeping out of session over email or something. There can be a lot of arguing there and it can cut out some time in session. Though I suggest doing the first lot in session so you can see for yourself how it all flows.
In the end having the right stats in nice but if your GM is flexible and you role play well enough I don't see why any person can't be the leader even an npc.
Remember you will be out in the wilderness a lot. Survival is a good skill as well as keeping track of how much stores of goods you have. The nearest shop might be 4-5 days travel away.
You are in for the long haul here. The game could take years of in game time to complete. Keep track of your age especially with animal companions. Your cavalier might need to switch mounts depending on how long the campaign goes. But it also means you have a lot of time for item crafting.
In keeping with that last piece. You are in for a long haul so your characters will have downtimes to pursue their own interests. Try to have a few non combat things your character likes doing. I had a bard who was writing the tale of the kingdom. He had two versions one with the full real accounts which was kept under lock and key as it contained state secrets and one 'bardic' version. It gives the dm more plot hooks to keep the game alive