there's no vowel between the K and the n. It's like the -(c)kn- in 'Hackney' or 'Cockney'
As pronounced, there is a weak unstressed vowel because k is a velar plosive. Don't make it as strong as the one in cockerney or people will think you can't speak German š
No, as I said, there's no vowel between K and N in German -kn-.
I'd never heard of Knipex the company, so don't know if it has some kind of special pronunciation. If it follows standard German spelling conventions, it'll be the same as in words like "Knie".
If that's a German name, there's no vowel between the K and the n. It's like the -(c)kn- in 'Hackney' or 'Cockney', only at the start of the word.