足る and 足りる are essentially the same word. Historically, only the former existed, and the latter has only existed since around the Edo Period. Though not much time historically has passed since the Edo Period, the latter form has largely replaced the former. These two forms do not belong in the same class of verbs, and so their conjugations differ as follows:
Both forms have the same 連用形, and in forms like 足ります・足りません, they are identical. Both verbs show that something is "sufficient/enough". For all intended purposes, this is a single word with fluctuation in form. This is likely because it has been a frequently used word for centuries. However, you don't necessarily hear people say the following all over Japan (though this would be said in some regions).
If you just barely have 5000 yen, that'll be enough.
There are set forms that use less commonly used forms such as 足る itself. The negative form 足らない is actually not that uncommon. Interestingly enough, ～足らず exists and is used a lot even though 足りず is not used at all. Old words and grammar go together.
1. 衣食足りて礼節を知る。 (Literary set phrase)
Only when basic needs for living are met can people spare the effort to be polite.
Using a long word when a short word is enough is a sign of manifold knowledge.
4. あなたの直観は、信用するに足る実績がありました。(信用するに足る is a rather common set phrase)
Did your intuition have any real results worth trusting?
I need 3,000 yen but I lack half of it.
She has apparently finally succeeded in correcting her lisp.
There is enough food for all of you.
8a. 言い足りない ＝ Not say enough.
8b. 言う必要がない ＝ It's not worth saying.
9. あの新作は論ずるに足りません。(Written language)
It's not worth arguing with the new plan.
The government probably has no choice but to cut frivolous items from the budget.
依存 means "dependence" and is used with に as a verb to mean "to depend on". Its most correct reading is いそん. However, the amount of people who read it as いぞん is growing. This is especially the case when it is used as a verb in 依存する.
Many small countries that depend on the economic strength of major powers exist.
The village's economy depends on agriculture.
Don't depend on his help.
Success depends on the method.
This phrase means "to be worthy of". It is equivalent to 価値がある．
That website is worth seeing.
That four year old child drew a picture worthy of adult appreciation.
～に及ぶ is found after both nouns and the 連体形 of verbs to show that either a certain final step has at last become so. In the negative, it shows that there is no need for the said action in follows.
It's not necessary to say so.
18. 彼は長ずるに及んで文才を現した。 （書き言葉）
He finally revealed his literary talent in excelling.
It has finally become an offense.
It's a little late to mention that.
Don't mention it.
There's no need for you to call me back.