Hasta La Motion!

Im am just starting out learning roto and paint techniques, i am planning to have a reel complete in the next 2 – 3 months. I just have 2 questions.

1. If i am to make a standard def reel (640 x 480), would i be better off rotoing hd footage first, then converting to a smaller res? this would make sense to me as the roto shapes would be easier to mask as the footage will have more pixels and less blur.

2. Im from Australia but am thinking about going to the UK on a working visa for 2 years, is there more work as a junior roto/paint in Sydney or London, generally speaking, any experiances shared about these 2 locations would be appreciated.

Thanks.