In English let's means actually come on!. It encourages the others for an activity. Are my examples below possible for "Let's talk about football, German etc."?
Lassen Sie nun uns Fußball sprechen.
Lass uns Fußball sprechen.
Lass nun Fußball sprechen
Los! Über Fußball sprechen.
And I would like know if reden and sprechen are interchangeable here?