1) yes you can. you make a action in a trigger that reads this.
action-
--disable (spell item casts) for player (number)
that will disable the item spell for a player. you can do it for each player. than just re-enable it when you want it to work again. very easy. that trigger is under the category player. it's up to you to decide the event and condition btw. i can't do all the work for you now can i?
2)no but a work around would be to just replace that item with a copy of it with the added abilty. basically just remove the old item and replce it with the new one and no one would know. make them all look the same but some have added abilties. or you could use the above trigger and just start with the item having all the abilties but at map intilization disable all the ones it shouldn't know yet. than when it should know them enable them for all players. that way would prob be easier. so just do that one.
.... Okay, but for the first one, is it possible to remove it for a specific item? Like I want to make it so that if you have 2 weapons, the one you pick up has it's abilities disabled.