Two questions:( What only two?)
First:On my spell casting characters, there are quick slots on the game interface page and when I click the red diamond another set of open slots appear above the action bar. How can I move spells into these slots? My spell casters are at about level 4.I have read and reread the manual, but I cannot move any spells into these slots. Also, do spells in the quick slots, the ones under the the quick weapons slots, active to use?
Second question, or is this third?,This one is related to the first question....
I currently have a number of duplicated spells already memorized by my casters, should I sell them?
Many Thanks, Muzzien

Right click the quick spell slot, and it should offer you a choice of your currently memorised spells. Click one and the quickslot should now be populated with the spell in question.

Do what you want with the scrolls, but keep in mind that mage scrolls in both Icewind Dale games are quite scarce and not all sold items can be recovered (some IWD merchants reset their stock - though I seem to recall reading that the EE changed this behaviour for at least one or two of them - and IWD2 has a couple of points of no return where you won't be able to get back to previous merchants), so if you are able (and decide) to later dual class a character into mage, you may want to hold onto the scrolls.

In this light, I'd note that Heart of Fury mode in IWD1 in particular, should you decide to undertake it at some point, almost mandates a mage heavy party (and thus possibly multiple playthroughs just to gather necessary scrolls) - heck, non-caster melee fighters have an increasingly difficult time of it very quickly even on regular Insane mode ...

Very helpful, thanks