Whom's

In English, whenever I hear a phrase with "whose" in it, 90% percent of the time it's not in a simple question. It's in a phrase like "I know whose cat that is.", being an english speaker, I have a hard time comprehending what exactly is receiving the knowing here. Should it, theoretically be "whom's" cat? More importantly, how does that translate into Russian? Something like "Я знаю чья кошку это.", or is there around 10 more forms of чей that I dont know about?

Я знаю, чья это кошка.

Hmmmmmm...

А кошка всегда знает, чьё мясо съела :p

Я знаю, чЕЙ это КОТ)))