When you are equipped with a magic staff, the spell should appear in the list of Spells so you can see the amount of damage it does.
In the original D1, a spell enabled by a staff would enable the associated icon under the list of Spells and provide details on Damage range and mana used. The Belzebub mod does not.
Yeah, but it's not vital. If you learn the 1st level of the spell you can check it's info, and all characters (even Barbarian with some +Magic gear and drinking a Magic Elixir) can learn at least 1 level of all spells by the end of nightmare. I doubt you will find a staff with charges for one of the high end spells (MeteorCluster, Blizzard, Apocalypse, etc) before you find the book to learn it, and for the lower level spells books are overabundant and these are the ones that spawn most often as charges on staves so it's likely you already learned them.
Then if you find a staff with the affix "+x to (some) Spell" the SpellBook will show the info for that spell.
Anyway, sometime in the future i will deduce how all spells have synergy with magic/spell level/character level and i'll put them in the docs.
Don't worry, when all my work is done i'll hand it over for examination. It will be easier to spot mistakes then to have him tell me so many things. And I don't want to take his time right now, time he may put into modding (i hope).