1. I don't know.
2. Maybe - depends on the firm, and the practice area and the economy (e.g. bankruptcy is starting to boom, and be extremely busy, and mergers and acquisitions and real estate are slowing down). Basically, the hope is that you'll at least be billing the minimum to get your bonus, and other times you'll be slammed depending on what kind of deadlines are going on.
3. No, crim law will not suffice, and neither will family law, most likely. There are exceptions here and there, and it may differ depending on what your definition of BigLaw is, but most big firms do corporate work - corporate litigation, corporate transactional work, corporate real estate, corporate taxes, etc. If there is crim work, it'll be criminal white collar and possibly securities work. But most large firms have to do corporate work b/c their fees are too high to be affordable to anyone but corporations or the rich people who run the corporations.
As a 1L, it sounds like you need to start doing serious research on what type of work is out there for attorneys.