1. How long should my gown be?
It depends on the type of gown you are making and why you are making it. A silk gown meant to be worn indoors can be long, almost reaching the floor if you would like. A working class gown should be shorter, with the finished length at the top of the back of your shoe or even slightly shorter. A gown meant to be worn out of doors should not reach the ground. You will wick up moisture and the skirts of your gown will become a sodden messy business.
2. Should my petticoat match my gown?
It is nice if you can to always buy enough fabric to make a matching petticoat. Putting both gown and petticoat together, automatically makes it a bit more formal in appearance, so if you want to dress your gown up a little you wear the matching petticoat.
It is not necessary to have the petticoat match, a contrasting petticoat can be worn.