I guess that is the way to describe it grammatically. But more importantly, it is just bad writing. The word "further" adds nothing to the sentence. And purists will be upset that it creates a split infinitive. Most people would say "increase" rather than "further grow" anyway. Linked In is a great tool for finding people, but not a place to learn a language! Go to the NY Times or the Economist or some other place where people proofread things before putting it on their website for examples of good writing in English. Anyway, those are my thoughts for this Friday! I hope that helps.

Yes, "further" is a verb. It is also an adverb and an adjective, so it is quite a flexible word. Your example uses "further" as an adverb modifying "grow". The sentence is fine. If you wanted to use it as a verb, you would write: "...to further the growth of their confidence..."

I agree with both answers below from Tom and Jonathan.

I have to disagree with some of the others. If FURTHER and GROW were both verbs, it wouldn't make any sense. I would say FURTHER is an adverb modifying GROW. It is true that it is rather redundant, i.e. if something is growing, it's already going further.