I’ll give you a very rough and vague answer to a question that would take a book to answer.
Since you are MIXING, the elements shouldn’t be “around” anything. They should be mixed to your taste.
As for levels, keep your eyes on the meters. Commercial and promo work rides at about -15 to -12 with peaks at -10.
Monitor your mixes through different speakers and mix according to what will be the final playback environment. Music tends to get eaten up in smaller tv speakers, but tends to overwhelm dialog in larger speakers…split the difference.
Dialog is king..always….if people are talking, better to play it safe and not have it even come close to fighting with the music.
So much more to add to this. Seriously, the question couldn’t be any broader.