

Regarding valence, both pronunciations I’ve heard and used put emphasis on the first syllable, it’s just whether the first vowel is long or short.
It’s one of those things that just doesn’t come up often enough to actually address it and nobody has ever misunderstood or challenged me whenever I’ve said it differently in conversation, during a presentation or afterwards, or in lecture. It sticks out as an example for me because any other words I was uncertain about definitely get challenged (e.g., route and router)

I think you meant rooter sounds ruder