Hey there and welcome! Internet marketing is booming quickly in these past few years and has been a really great demand for this small niche. It's a good industry to get involved in if you're willing to spend a lot of time and effort into it.

Here's my answers to your questions:
1. IM and DM are different, but can be used together to help out each other. Take a look at http://www.bls.gov/oco/ocos020.htm as it gives an overview of what it looks like to be in the marketing industry
2. I wouldn't say you technically need a degree to actually pursue marketing as it is a lot of learned skills and experiences. If all else fails, you can always succumb to http://www.marketingdegree.net/ to get SOME education in, so that a degree will help you stand out to employers
3. You always look into marketing music on the internet? Maybe start your own music company? Then that will lead to ways on how to market your company via the web.
4. You will need more than those skills to succeed, but it's nice you have a broad field of experience and knowledge--which will help you be diverse and malleable.
5. Umm...for mediation...I wouldn't recommend that...if you just stay positive and follow what you've been called to do, then you will be successful.

Good luck and try to see what it is that you're really passionate about.