Correct me on the following:

1. A thief with scrolls at 100% and no arcane lore will still fail to recite scrolls a lot.

2. A thief with scrolls and arcane lore at 100% will recite scrolls with the same success rate as any other class with the skill at 100%

3. A thief with 100% in scrolls, lore, arcane lore and pen will recite scrolls with an even better success rate

Or do thieves need all four skills at 100% to recite scrolls with the exact same success rate and spell level as a mage?

I'm pretty positive pen and lore are irrelevant.

Says proficiency with lore/pen adds extra benefit.

for help arcane lore.

Well, crap. So it does.

That being said, now that I look at the code, the difference between 75 pen and 75 lore vs. 100 pen and 100 lore isn't that huge. You shouldn't skip those skills but even I'm probably not enough of a masochist to spam pen to 100 for it.