do all spells have a cast time?

[Etagloc]

or are there some that are faster, like a minor firebolt or a zap ?

[Q_taro]

Stronger magic tends to take longer to cast.
If you learn Articulacy, which is an argument for Sorcerer LV9, the casting time will be reduced by 15%.
It is possible to speed up the casting time slightly with Wyrmking's ring.

[Etagloc]

arh ok, so you can shoot minor attacks with your staff. neat

[Migromul]

"skill"-spells, yeds. the core-attack of rhe staff: no. Focuse bold, though, yes. I like to cast the quick bolt firve times and hold the button witht the last attack to get forcuse bolt. So you don'T waste the first one.

But I think, this is the itneresting part of playing amage/sorcerer: the cast-time.

There are augments however, which more or less guarantee, that your spell will get through: Bastion (rank one warrrior-augment) protects from physical attacks
Gravitas (rank 7 or 8 sorcerer) will make it more difficutl to knock you down
inflection (mage, don't know the rank) works like bastion, but against ALL damage and only while casting.
Intervention (mage, don't know the rank) reduces debilations-time like burning, maybe also reduces the likehood to get debeilatied at all. (but only from elemental debilations: e. g. frozen, burning, thunderstruck.)
Awarness (rank 1 socerer) reduces direct elemental damage (NOT the dot-debilation-damage however)
And last, not least: Articulacy and the worm king ring (the real one) reduces cast time. Articulacy is a rank 9 sorcerer-augment.
If you're playing sorcerer, try getting a second with the same spells as you have. They will "spell synch" then, which reduces the casting time. You can do that as well, if you see, them casting.

Edit: you don't need to fully charge a spell: Every filling for the chrage-bar makes the spell stronger, however. But you also can just charge up one bar: (I like to do that against the annyoing harpies with ingle. One charge get them down or even kill them with a good staff.)
The big sorcerer-spells are charged up automatically at least one bar and will releas automatically then, if you don't hold down the button. Normal spells, however, will get interrupted afaik. (frigor may be an exception.)

[TotalWarlock]

basic attacks are still considered magick so that kinda what youre looking for
otherwise youre kinda stuck using the augments and wyrmking's ring for cast speed
the magick in this game is definitely worth the time it takes though