Looking good! I didn't catch this thread until just now, but you've done a good job dealing with your situation.

The only suggestions I would have made (pre-construction) was to go with ridge pipe. It flows better and does not silt up nearly as quickly as the flexible pipe. It is also stronger and will not collapse as easily. It was a very smart move to run a separate pipe for your downspouts. Putting water (and leaves) from the gutter into an area drain is the best way to plug it up with roots and decaying material. The dry-well will eventually fill with leaves and material and plug up.

My last comment is in reference to your question about running the drain pipes under the sidewalk to the street. Frankly I wouldn't worry about it unless you want to cut the sidewalk and re-pour it, which will get your city streets department involved. From your pictures it looks like you have tons of fall from your house to the street so I would install one of those pop up drains mentioned earlier and just let it drain across the sidewalk. You could also purchase a small composite catch basin from your local HD or Lowe's and place it right at the back of the sidewalk. Either setup would work well and give you a spot to clean out debre that would eventually plug all of your hard work.