Help with Upgrading OS

Hi Everyone,

I plan on upgrading my OS from Leopard to Lion and hope you can help.

Here are a few questions -

1) I don't have Snow Leopard which is between Leopard and Lion. Does Apple require users to have the penultimate OS (Snow Leopard) in order to make the upgrade to the latest version (Lion) or is it okay if that one is skipped?

2) Last time I did an OS upgrade, I remember backing up all my files. Does making an upgrade erase all current files and programs?

3) I also seem to remember that when I backed up all my files by dragging and dropping, not everything was fully copied. For example, when I dragged & dropped my itunes library over, it copied the titles of the playlists I made but not the actually contents of the playlist. Or when I dragged & dropped the address book over, it copied names of people over but not any of the specifics (numbers, addresses, notes etc.)

Also if you are kind enough to answer these question, please feel free to offer advice that you think may be helpful when I upgrade. I am concerned about things going awry.

Thanks and hope to hear back from people!

 

So, I am currently using Time Machine before the upgrade.

My macbook pro HD says I have 233GB used, but Time Machine says it is backing up 181GB.

Why is there a discrepancy? Is there a box I am not checking when backing up? I am obviously not backing up some files. Any explanations and advice to what's happening? From Time machine preferences, I am not excluding anything from being backed except for the external HD itself.