The frogs are isolated from the blades and switched polarity via a micro-switch in the tortoise slow-motion motors I use.
The stock rails and blades are electrically bonded together. Rails are painted prior to ballasting (applied dry, sprayed with water (plus a drop of washing up liquid) and held in place with matt medium – dilute PVA). Railmatch sleeper grime is then brushed on once the ballasting has been tittivated.
A track template (paper) is taped underneath first to ensure everything is square and sleeper spacings are correct. Track gauges ensure gauge is correct too. Plastic cosmetic fishplates are glued between track panels, or where longer rail runs are used the top and bottom of the rail is cut into with the fishplate hiding the fact that the cut does not go the whole way through the rail. Electric feeds are soldered to the base of the rails to stay hidden as ballasting is minimal!