YouTube – How to Fix Channel Art Upload Issues

Picasa - A photo storage service from Google (also an application by Google) Google+ - The social network from Google

Both Picasa and Google+ are from Google, and to make it easy to manage Google accounts, Google is now integrating Google+ with most of their products and Picasa is one of them.

I suggest you to switch to G+, it has more features and all your products will be managed from one single profile (your G+ profile). Try it, G+ is better.

No, unless the owner wants to do it there is no way that you could claim another username. just find another name, for example mybusinessofficial or anything else.

It may be helpful to read the YouTube's username trademark policy.

Problem is, they're probably not infringing your trademark, as you may know, just using a name doesn't infringe a trademark, what is important is "how" they use it. that said, if they even try to upload any content, similar to yours, which imply that their channel is connected with your brand, then you may use YouTube Trademark Complaint Form to take down their content, their account or assign it to yourself.