Shift+'Apple'+ "A" gives you your Applications folder. Find the icon of that particular app and click+drag it back to the dock.
Or, find the app using a search. Double click the app to start it. When it's open, the icon will be shown in the dock because it's an active app. If you single click+hold on that app's icon in the dock, you get a dialog that lets you KEEP ICON IN DOCK.
You can then click+drag it to place the icon in a different place within the dock.
No idea about your G3>TV idea. I'd suggest looking on the Apple.com support site, which may have a specific section for the G3. Here's a file regarding the G3 laptop. Check to see what connectors are on the back of your machine.
Here's something about the G3 tower, but i don't know if it's what you need: