In English it is sometimes permissible (but not necessarily (always?) proper grammar) to "split" a verb infinitive with an adverb. For example, consider the placement of "quickly" in the two following sentences:
I was able to get up quickly.
I was able to quickly get up.
I have a related, but slightly more specific, question about a similar notion in French. In the two following sentences, is it correct to place the adverb before the infinitive (as opposed to after it)? If is so, is there a specific rule as to why?
Tu me sembles de bien connaître …
Je serais très heureux d'encore vous ("vous encore"?) aider !
My intuition tells me that it's sometimes correct to place the adverb beforehand, but I don't know why. Maybe it's related to why sometimes (always?) it's correct to say "ne pas" + infinitive?
Edit - Note that my first french sentence, I've misused "de" (there shouldn't be a preposition there). I've left it as is to ensure the responses I've gotten don't need updating.