hey DM what software/coding are you planning to use? Browser based or client based? MMORPG that looks and plays like FFT (strategy RPG)? Or one that plays like FFXII or that has a text interface?

I will say, the job classes are VERY ambitious for the start of a new game, whilst it is good to have these laid out be very fluid with them too. Now depending on your interface and browser/client decision you have different limitations. A major one in the MMORPG I work for (TPS) is balancement and believe me the combat there seems simple enough; you have skill you have stats what modify it, you have around 14 different classes of weapon and about 10 tiers of weapon you also have different armours and yet balancement is a fine tuning issue. 66% chance of striking with a 1hit kill move is not a good idea it'll hit more often than not and whilst if there are monsters in the game can you imagine if there is PvP? Everyone would just have these skills and just go around using them endlessly. Also theres other issues but I need more information before I try and advise you.