As a fellow player of MMORPGs, I think I have some few ideas to share as well (Mainly to #4): To #4:
If you want to not focus on the Class system of a typical MMO, you may instead try to instead focus on leveling the weapons that you can use(Swords, Axe, Bow), where you can invest a skill point on a certain weapon skill, for example, when you reached level 2 from level 1 on your Bow, you now have 1 point to spend on your Bow skill tree.
Furthermore,
MMORPGs thrive with a party of players! So with the above mentioned weapon skills, you can either create a DPS player, a Tank, and then a Support player.
Just an advice on building the game itself:
Try to build up the PvE elements of the Game, mainly the Story, so that your game will have more depth to it, and a good lore invites a good community.
Then you can start with your PvP elements, guild wars, 1v1s etc.
Good luck on your MMO server! I am excited for what you will bring to the community ^^