Looking good! Do you plan to lay the track on any cork roadbed before you ballast? I would highly recommend it, as most prototypical track is elevated above "street level." As far as the lake goes, there are a number of good resin products that mimic water to a high degree of accuracy. It's probably too late, but I would have given the lake an inlet that "flowed" off the edge of the table - it gives the illusion of a less enclosed space. Here's an example of what I mean from my tabletop N layout.