Of the three skill groups you listed above, I would say all three would be greatly beneficial to any marketing firm. I'm not in the marketing / PR space, so I can't comment directly, but I'll break out each one quickly below and why they could be a benefit:
- Coding: This is the one I would stress most for anyone moving out of school and into the job market. Development skills will absolutely always be of benefit. The ability to manipulate a machine to quickly make edits to a website, or application cannot be stressed enough. You don't need to be proficient in 15 languages, but if you have a core base level knowledge in base languages (C++, Java, Python, etc..) you could potentially make necessary changes yourself or at least go into negotiations with a contractor on a more educated footing.
- Trilingualism: Awesome. Exposure and familiarity with different cultures and languages is always a plus. Marketing / PR firms with international presences would love this ability.
- Graphic Design: Another great skill set that can be supported by a development background as well. Same as above, being able to quickly make adjustments yourself allows you and your company to be more agile and save funding for other purposes rather than needing additional talent.
When you're applying for jobs, coming to the table with a breadth of experiences like this is a huge plus. Anytime you can develop your portfolio (GitHub / CodeCloud for coding, examples of Graphic design you've done), will benefit you in these discussions. As lead interviewer within AT&T, I love to see examples of what candidates have done outside of course work to see what they are most passionate about and observe examples of how they have gone above and beyond.