Just out of curiosity, but is there any tricks to the trade of magic in Arena?

I did create my own spell, a touch spell, but it seems to have a long range compared to touch spells in Morrowind and Oblivion, to a point.

But when I do a ranged spell, I can't tell if it hits the target. For all I know, the explosion of fire occurring on the screen is off to the left a little to far, and behind my enemy. Is there something about projectile magic I'm not catching on to?

Yeah, unfortunately projectile magic in Arena is very vague and the effects aren't too leading. You just have to use the enemy's death or bleeding as an indication.

Not sure about the touch spell as I haven't played Arena in a while. Arena may simply have a longer touch casting range than Morrowind and Oblivion. Is it ridiculously long range, or still fairly believable?

It seems reasonable enough considering the range for melee strikes as well.

So... Projectiles never really hit in Arena do they? Bugger.

Yea, projectile spells are unreliable in Daggerfall as well. Very hard to aim properly, and they often just fly right through enemies. Best to use area spells and aim for their feet. This is probably why being a mage wasn't incredibly awesome until MW came around.

Projectiles in Daggerfall tend to arc, it's a pain. Aim a bit higher when casting them.

So... Projectiles never really hit in Arena do they? Bugger.

Yes, they do hit. Usually, in fact, in my experience. I've never had an issue, except in the beginning when I kept hitting doorjambs.