Remember that you can favorite a question to find it quickly later and be notified of answers.
You can see the questions you've answered in your profile (click on a tag to see the questions in that tag). If you want to know about questions you've commented on, there's no way to make such fine-grained searches in the UI, but you can use the API or the data explorer.
From the API, you can retrieve the results of a search in a parseable form (JSON). For all the questions in a tag, use the
questions method. For example, this request returns the 100 first questions in the
cryptography tag on Security Stack Exchange, with answers and comments, sorted by creation date. (If you want more than 100 questions, you need to make multiple requests.) From there on, a small script on your machine can extract the questions where you have or haven't participated.
Look around on Stack Apps if there's already a browser script or application that might help you.
The data explorer gives you read-only access to a slightly stale copy of the Stack Exchange database. You can make rather complex queries if you know a bit of SQL. For example, I just wrote Questions I haven't participated in, in a particular tag (seems to work but I haven't tested much), which you could adapt to “questions I've commented on”.