Hello @julielfifield,
Let me answer your questions one by one.
1: There is no Tag family that can visualize the Build-in Offset parameter of certain Revit categories. So if you want to Tag for instance the Offset of a Pipe Fitting, you need to copy the Offset parameter over to your own Shared parameter. For instance, "Offset" to "My Offset".
Add the shared parameter as a project parameter to your Pipe Fittings first.
Create your own Multi Category Tag family that shows the value of your "My Offset" parameter.

You can do that by using a Dynamo script like the one I share with you.

This is a simple Dynamo script that reads the value of the "Offset" parameter of the selected Category and adds that value to the parameter "My Offset"
You can use it also for other parameters and other categories.
See attachment for the Dynamo script.
Note: you can add this script to your Danamo Player list.
2: When you want to Tag the inner radius of an Elbow you need find out if the parameter that is used for the radius is a family parameter or a shared parameter.
If it is a shared parameter, then you can create a tag that shows the value of that parameter.
If it is a family parameter, so NOT a shared parameter you can't show that parameter in your project unless you change it into one.
You could open the family and replace the radius parameter by your own shared radius parameter.
3: Dynamo lessons
You can find lots of Dynamo lessons online.
But first I would advise you to go to www.dynamobim.org\learn and follow the video tutorials first.
There is also a forum where you can learn more from others or ask a question. There are a lot of forum members that like to help you.
have also a look at:
https://www.youtube.com/user/AutodeskEd/search?query=dynamo
If my post answers your question, please click the "Accept as Solution" button. This helps everyone find answers more quickly!
Kind regards,
Robert Klempau
Senior Consultant AEC
Cadac Group AEC BV