Learned counsel from your state have answered. The best part of your post is its last sentence.

What is the difference between vvc 21453a AND cvc21453c ? Is one better then the other

You appear to have a defensible case. Did you get a ticket for one or the other? Best to consult a local defense lawyer.

If I understood your post, a warrant has been pending for 3 years? Then essentially the 2020 date has been effectively tolled. Consequently,...

Why didn't you complete community service? It's only 15 hours! You could do that in a week, certainly two. So do it.

If wrong (but similar) CVC is cited on a ticket, not amended before trial, and I base defense on it, will case be dismissed?

Best thing you could is stop trying to play lawyer and hire an actual one. If you cannot afford a lawyer, ask the court to appoint one.

Re- Should I schedule an info pass?

Your question is very confusing. Try asking it again.

What's the possible outcome from judge?

You need a local criminal defense lawyer. If you cannot hire one, ask for a public defender.

Can I appeal a plea barging if I feel like I was pushed into it and not explained it very properly?

Follow the sound suggestions made by my colleagues.

Will he face jail time?

He is facing prison if convicted. He needs a good criminal defense lawyer ASAP.

Learned counsel from your city has answered you.