Problem 2 is solvable. The description is taken from the latest non-prerelease version of the gem (not including yanked versions). (See more info about prerelease gem versions here.) Right now, your gem has 3 versions, and the two non-yanked ones are both prerelease (they have letters in the gem version). If you push a new version of the gem, even if it's 0.0.1 or something, that's a "release" version, and it will be used for the description instead.
I made a little test gem here to demonstrate what I'm talking about -- notice that the description page is taken from the latest non-prerelease version (0.0.1, in my case.)
There is no self-serve way to "solve" problem 1 -- Rubygems.org will always display your gem versions in semantic versioning order, from highest to lowest. I'm not sure why this is a big issue, though -- most people typically won't look at the versions page. Yanking will mask the bad version in most situations and, as the documentation says, will probably "do the trick" in this case.
If you really want to permanently hide the traces of the yanked gem and remove it from the versions list completely, you'll need to contact the Rubygems staff and see if they're willing to help out.