This is an allusion to the movie "The Big Lebowski". It's just a funny easter egg and makes 0 sense if you're not in on the joke.
Consider yourself insiders now!
In many native accents of German, there is very little difference (if any) in pronunciation between ‘Kal’ and ‘Karl’. This is the correct way of pronouncing it.
What is the rule for dropping the indefinite article like this? I know it's true for jobs, but "expert" isn't a job. I'm pretty sure it's not just universal any time you say that someone is something. For example, you wouldn't say "Ich bin Mann." So, how do you know when to include it and when not to?