Welcome and happy birthday! The color of your iPad is a personal preference of course. The size depends on what you want to do with it. Music and video files take up more space than anything else. Books, apps, etc. take up comparatively small amount of space.
Here's how my 64GB iPad's memory is being used:
I have about half of my music library on my iPad, one full-length movie and a bunch of video clips as well as a couple of photo libraries. The rest are apps and about a dozen audiobooks, some podcasts and other miscellaneous files.
A good rule of thumb when buying any computer, iPad or otherwise, is to get as much memory/storage space as you can afford at the time. It's really more important with an iPad since you can't add more storage space later (although external hard drive options are becoming more practical, but that kind of defeats the "mobile" value of the iPad). Although it won't pay for itself, additional space will improve the resale value of your iPad when you decide to upgrade one day.
The issue with the "bleeding screen" seems to have been limited to some early stock. The problem pops up now and again but it's a very rare complaint anymore. Your new iPad will carry a full one-year repair/replacement warranty from Apple (with a 14 day no questions asked return policy). Apple is notorious for excellent customer support so I wouldn't give something like that a second thought.
My two cents. Others will probably chime in. Enjoy your new iPad!
