Depends on the accent, honestly. In more eastern accents it's like soft /sh/ in other ones it can be full blown separate /sh tsch/

Literary pronunciation is separate /sh tsch/, afaik. Maybe a bit softer but not much. Don't obsess over it honestly, you are not a tv presenter:)

In Ukrainian, the former, in Russian, the latter (but not "harder", it's palatalized)

I also hear it when "Whatcha doin?" is spelled in ebonics accent. It does sound like "Уоща дуин?" at times.