1) When the starter is finished fermenting you just throw it in the fridge until brewday. That way you can decant the liquid off of the starter.
4)
http://www.mrmalty.com/calc/calc.html
5) The only thing wrong with too big of a starter is that you may not get quite as much estery flavour as you hoped. Many flavour compounds are a result of cell division and pitching too high leads to a slightly less flavourful beer.