DLS "best practices" for routes


As I head into another winter season here in the Northeastern US, when my free time typically picks up and I return to Trainz from my annual summer hiatus, I'm again planning to take another stab at a route (or part of) that I've been fighting with off and on for years. Even if I end up shrinking it to something more like a small switching route/scenario, I'd like to try to get something release worthy by the time my free time ends around March.

My question is this -- what are the best practices or goals for DLS routes as far as what can and can't be used? I know the overall goal would be to stick to what is already available on the DLS, but in some cases that doesn't seem possible. Some particular instances I can think of involve assets that for whatever reason are missing dependencies (even as simple as a corona, which boggles my mind as to why the main asset would be on the DLC but a corona by the same author would not) - I presume it's not acceptable to include the missing asset in my route?

Is there a combination of search parameters I can use in Surveyor (classic or 2.0, as I'm still debating the upgrade) that would give me appropriate content both on the DLS and already on my computer (downloaded or built-in) that would result in the best options for use? I currently have a figurative ton of content that I've gotten both off the DLS and installed from CDPs from third party sites, so filtering out the third-party, and/or stuff I already have that may not be available on the DLS anymore, or is version-appropriate for TS19 (or TS22, if I upgrade) and up, would be an important step.

As an extra to that, is there an easy way of verifying what I might already have in the route that doesn't fit these parameters and removing/replacing it without finding every individual asset in CM to check it out, and then going back into the route to find and replace it?
Select your route in CM and then select list dependencies recursively. In the new window select the + for a new line and add "on download station" = false.
+ for a new line and add "built-in" = false.
This eliminates all built-in and DLS content from the list. You can add others like payware (DLC content), and packaged. This leaves you with all the assets not available to others in your route.
From the Trainz Launcher select Start Trainz, on the top left are 3 bars, select Settings, under General settings check Show object/track/train KUID in Surveyor.

When in Surveyor when you click on an object the kuid willl show on the bottom right. It will be color coded to indicate DLS, Payware, Modified etc.

Not sure what all the colors are, maybe someone has that list available, but if I remeber right white and yellow are safe.