There is a manual.
Surveyor 2.0 - Surveyor 2.0 (trainzsimulator.com)
While not complete, it does say a lot of useful stuff.
For the issue that we have here, Tony answered the question in another thread.
Surveyor 2.0 feedback thread - Page 13 (auran.com)
Th gist of it is
Set the filter to selection
Change the category to the type you want such as track, for example.
Now only track assets will be selected and manipulated and other things such as fences and grass, or buildings will not move. This is exactly what I was looking for.
If you want to select a particular asset, select that first on the route using the eyedropper. This will, or rather should, bring the asset up in the asset list.
With the asset highlighted in the assets list, right-click and choose copy.
Paste that asset in the selected asset box, also used to search for specific assets. Now only that asset can be selected and nothing else.
I used this last night while editing a route. Very useful, indeed!
Now for textures.
Click on the brush icon.
Click on textures icon on the selection box.
There is a bug, or it appears like one for me where if you have thumbnails viewed the list doesn't change, but it does if you have a list view.
Type the name in the search box or scroll until you find what you're looking for. The rest is straight forward. You can set the size and scale as before.