I had no major problems riding the Mezzo in the wet, although spay can come up the end of the rear mud guard and make a mess. I fixed this with a piece I a cut out of plastic fruit juice bottle attached to the end of the mud guard with a good quality double sided sticky tape. Here is a photo of the mod, not very pretty but very effective.



There might be an adjustment for the clip that holds the front wheel in place, I never had a problem with it I have not had need to check. Take a look at the instruction for the bike, they can be downloaded from the Mezzo web site. Fitting in-line skate wheel in place of the small wheels makes a big difference to rolling the bike. A 4 wheel rolling kit is even better and means you can take the bike into places where it would otherwise be a pain to carry. I made a a full rolling kit for my Mezzo you might be able to do something similar, see the Mezzo upgrade thread here http://www.bikeforums.net/showthread...upgrades/page3
For lighting I use a cheap red led rear light fixed to the seat tube. Mezzo recommend using the Cateye TL-LD1100 rear light as it will screw onto the rear of the rack in place of the reflector. Fro the front light I use one these http://dx.com/p/universal-adjustable...diameter-31871 with one of these http://dx.com/p/flood-to-throw-zoomi...nt-3-aaa-26800

The commuter bag is quite useful and much taller than standard rack top bags, its also quite substantial so its not the lightest of bags. Recently I bought a couple of Vario rack clones from Lidl to use with my rucksack and been very happy with it although they are only rated 5kg but its enough for waterproofs, tools and a drink bottle.