Help/Advice for Weapon Style Modding

I’ve begun working on a mod which edits the Weapon Styles within the EE games, to go along with my suite of 3.5 edition tweak mods, the purpose of which is to make minor tweaks which replicate several balance changes introduced in 3.5 edition and pathfinder; this latest mod, as its name implies, deals with the weapon styles in the proficiency screen.

I’ve come here to ask for some advice from some more experienced modders. Despite having made a few mods, I’m still quite an amateur with weidu.

Here is the mod, as is.

Now, I’ve finished the base aspect of the mod (which seems to be the simplest part), in which the STYLBONU file is replaced, and the “Weapon Style” strings for the descriptions have been updated (which I’ve made compatible with BG1EE, BG2EE, and IWDEE). This all seems to work fine at the moment, though please do notify me if any of my coding so far shows a problem, or if I approached it in an inefficient way. But what I require help with is several other parts I need to add to the mod, whose method of creation eludes me at this current moment.

First, I need to make a weidu code that will easily edit the existing WEAPPROF (where the number of proficiency selection and limit per class is set), rather than simply overwrite it with a pre-made file, in order to account for new kits added by other mods.
Here is what I need to accomplish through weidu: I need to change all “3”s in the “2WEAPON” row into “2”s; I need to make all Thieves, Bards, their various kits, and multi-classes have “2”s in their “2WEAPON” and “SINGLEWEAPON” rows; and I need all mages, sorcerers, and their respective kits to have “1”s in their “SINGLEWEAPON” and “2HANDED” rows.

Second, I want to make it so all Quaterstaves can no longer backstab (so there are no longer any two-handed weapons that can backstab), but I could not discover what determines whether a weapon can backstab within the files. Is it determined within the .itm files or somewhere else, and then how should I code that change.

Third, I want to add a passive modifier to all Rangers, given at the first level, that improves offhand thac0 by -2. Now, I know how to create this ability, and add it to the Ranger clabs manually. But how can I program it in weidu so that the mod will always add this ability (I assume through a new row in the clab) to each and every Ranger, kit, and ranger-multiclass that it detects in the current game? Again, so as to account for new Ranger kits added by mods.

As always, thank you for your time.