1) You didn't explain what you tried to do and/or how it failed. There are many ways to get to phpMyAdmin. The "easiest" way is probably from the Control Panel-->Goodies-->Manage Mysql acreen, and click on the phpMyAdmin link next to the hostname. Of course, this won't work immediately if you just created the host, as DNS has to update.
2) You now have an empty directory at your site. I can't really help you much as I have no idea what you did in the panel (name a new host the same as your domain, for instance?) but I'll guarantee you that your files did not "disappear" just because you "added a database". Fortunately, that situation should be easy enough to rectify by replacing the files from your backups (either your own or the Dreamhost maintained ".snapshot" directories).
3) There is no "new" setup for Dreamhost's MySQL - the only significant change in the last year was the ability to use the same users across databases and to host multiple databases within a host. It's unfortunate you are confused, but "it made me screw up" is a pretty ignorant remark. If you didn't understand it you might should have asked for help before you mucked about with it. You are right that it "shouldn't take..three hours just to figure out how to make the database, and 2 hours searching to figure out how to connect to phpMyAdmin"; once again not knowing what you did or how you are attempting these things, I'm not sure how to begin offering help.
You might review the DH wiki - there is a lot of help there regarding the use of MySQL on Dreamhost. Alternatively, if you actually ask a question, or at least explain what you are attempting to do, or how you did what you did, I might have some idea of what you are confused about, and be able to offer some real help.
As it is, all I can tell about your situation is that you are frustrated and impatient. That's fine, and I can sympathize, but I can't really help with the information you have provided.
If you are having a hard time figuring out what to ask to get some help, this classic link on "How To Ask Questions The Smart Way" might be helpful.
Seriously, if you can articulate what it is you don't understand, I'll try to help.