for 1, as said before, "you too � or �same to you � sounds better
In 2, performing bravely makes me think of pussy riot or other groups who have reason to fear something. A performance can of course be brave or daring but about the performers it sounds kind of awkward.In 3. I would replace although by nevertheless
In 4, is is also possible to replace "what" by "as"
I didn �t quite understand the question in 5, happy-happily and easy-easily share the same meaning, hard-hardly and late-lately have different meanings (like the well known high-highly)