What is best way to connect wirelessly to mac mini from macbook, file sharing or screen sharing?

I am interested in purchasing a mac mini, and basically using it as a repository for files that both my wife and I can then access from our macbooks without any cables (i.e., through our home wifi network). Based on what I have read, it appears that I can accomplish this in OS X lion by either using file sharing (http://support.apple.com/kb/HT1549) or screen sharing (http://support.apple.com/kb/PH4306). So I have a few questions for those who have travelled this path before:

1) Is either method easier to use then the other (more foolproof)?

2) Is either method faster than the other?

3) Regardless of which method that I use, can i configure the mac mini to "sleep" so as to save energy, but wake up when we try to access it from our macbooks?

I would welcome any other feedback folks have on the relative merits of each approach.