What would you say is the biggest improvement in terms of gameplay from the original Majesty?
In my opinion the most important gameplay improvements are party forming and lords appointment.
Will you be adding any new mechanics to the game
I think we'll not. We just haven't enough time for that.
Will the lords continue to rise in power and gain items in subsequent missions?
Yes they will.
If you've hired a lord and finished the mission - will he go back to the level and inventory where he was made lord or will he rise until he hit some levelcap?
If you finished the mission, lord will save his level and items in inventory in the end of mission.
By the way, there is no levelcap in the game at all.
Is there any limit to how many lords you'll be able to choose from? If you can make one lord after each mission, there will be quite many lords after a while...
One mission - one lord. There are 16 missions in the game. Thereby maximum amount of lords is 15.
Are all heroes able to become lords?
Yes they are, there are not such limits for heroes to become lords.