Forget the dynamo and just buy a set of decent lights. Will cost less and work better. You can take them with you when you return home, and remove from the bike if parked outside or not needed during the months with longer days. Lots of rechargeable lights that put out a ton of light (even though light doesn't actually weigh much, if anything). Plenty of so called "city bikes" out there that would met your needs. However, as I would never actually ride one, can't really make any specific recommendations. Most decent size bike stores carry something that will meet your needs, such as REI.