Alrighty. I've done up a quick document of
stats
That is a description on how the stats will look like to the player, it will be of limited help to a scripter trying to implement those stats...
For example, you state that the physical stats should increase the character's carrying capacity. However, items in RM have no weight, are carried by the entire party (one inventory per party only) and independend on what the description says the party can carry 99 of each item.
So in order to implement that part, you would have to first implement or limit such a carrying capacity...
However, there are several scripts already available that might help you on the master script list, I suggest you check that list. For example there are scripts for extra stats (which will do nothing unless you use those stats in the damage formulae), scripts for limiting carrying abilities or making actor inventories (instead of party inventory) and more.
Follow the link in my signature to some sample games (where you can see what others have done) and the master script list.