You're asking enough questions for a book, really; maybe a few.. If you'd like some primary material for London middle-class life, one classic memoir would be Molly Hughes's . A comic picture of urban middle-class life could be found in the Grossmith brothers' Diary of a Nobody. Perhaps some others can suggest good secondary sources.

I would recommend What Jane Austen Ate and Charles Dickens Knew for a general look at the middle classes of the era.

In general, people dressed as well as they could during this period (as with most periods). This meant at the very least distinguishing times of day with casual morning dress and more formal business/day dress. "Middle class" spans such a large section of society that I can't be really specific about how exactly it would break down - a clerk's family would not have that many changes of dress and would probably spend more time dressed down than up, but the wife of a successful doctor or lawyer could have a breakfast dress, a couple of silk day/afternoon dresses, dinner dresses, and at least one full evening dress. If you're looking for a more detailed answer, I can probably provide one with some more details on what you're looking for.