Is it possible to move pictures posted in MobileMe gallery to iCloud?

Here are some of the answers to your questions regarding iCloud.

Is it possible to back-up the music in my computer, if it crashes, using iCloud?

Actually, yes – you can download all your music files – That is if you set up your new computer with the same iTunes account you used to purchase your music.

However, this only takes care of music you purchased from iTunes. If you have a digital library of ripped music, you should also sign up for iTunes Match when it becomes available, as it will allow you to "back up" up to 20,000 non-iTunes music files to the cloud.

Though you have to spare around $24.99 for a yearlong subscription for iTunes Match.

And regarding with moving pictures in MobileMe to iCloud, you could check these links for other references: https://www.apple.com/icloud/, 

https://www.macworld.com/article/1160380/web-apps/icloud-what-you-need-to-know.html

Hope this helps you.