Non-combat abilities fall into two major categories: Skills and Languages.

1) Languages

At level 1, each character starts with 100% fluency in their native language (normally Common), plus a number of Language Points equal to 3 * Wisdom. Each LP buys 1% fluency in a language. The fluency percentage affects how easily and completely one understands a language. At level 15, each character gains (50 + (2 * Wisdom)) LP. Every 15 levels afterwards, and also at level 100, the character gains a number of LP equal to twice their Wisdom. Beyond level 1, however, the character must actually have some way of studying the language in order to learn it. [Unused LP may be used later, as soon as the character has an opportunity to study a language.]

2) Skills

At level 1, each character starts with 3 skills, plus one additional skill for every 10 Wisdom above 30. The same number of additional skills is gained at level 15 and every 15 levels afterwards, and also at level 100. Skills may be just about any sort of knowledge of little immediate value in combat - alchemy, hunting, thievery, and so on. Spending more than one skill slot on a single skill may result in more advanced knowledge; a perfect knowledge of Alchemy, for example, requires 4 skill slots beings spent. A skill of great value such as an Identify spell might require even more skill slots - perhaps one for every class of item which it is to identify.

With languages, in regular conversation the average person will use roughly a 50%. Somewhat more complicated subjects would be a 75%, and specific technical stuff reaches 100%. You could use your system for documents, I suppose, but chances are it'd be written in a basic complication level. [A character with 50% Elven would  not stumble over elven childrens' books, for example.] Any character with a comprehension level lower than that would get a % of the document equal to what percentage of the complication level they have in comprehension. That's not as complicated as it sounds...

Note, however, that comprehension doesn't necessarily imply understanding - for example, an advanced Elven book of alchemy would almost certainly be 100% difficulty, but even with a 100% knowledge of Elven, the book would do you no good unless you also had an advanced knowledge of alchemy.