I'm Aussie, so I'm automatically wrong, but here in Australia it's typically pronounced "caysh". It's a uniquely Australian thing, saying cache this way outside of this country will get you looks.

Don't worry, you're not alone - Kiwis do the same.

Cache has no cachét, if done right (other than speed of access)

I had a boss who did that many many years ago and it was like nails on a chalkboard. I'm glad you have corrected yourself. :)

I heard cash-ee and cage. Of course, it is cash like cache is king.