I would always prefer to do:

"There is no greater joy in life than typing a sentence, realising it needs a clarification, a caveat, an addendum (in the same sentence, not a new one) and, guess what, parentheses are right there for you."

> There is no greater joy in life than typing a sentence and realising it needs a clarification, a caveat, an addendum (in the same sentence, not a new one) and guess what? Parentheses are right there for you.

That's what I'd do. Note the conversion of the first comma to "and," as well.

The parentheses bind tightly to "an addendum" and change the meaning