Q: Using albums...

I have a few questions about albums and how they work or how I would like for them to work on my iPhone 5s:

1)  I created a specific album so that i could find certain pictures quickly.  Is there anyway to create another album, but have any picture or video that I take to go directly into that folder?  This way I wouldn't have to move it from the camera roll to the album?

2)  Camera roll and photo stream confuse me to no end.  I understand that camera roll is what's on my phone and photo stream is what could be shared by my other apple devices.  What happens if I turn photo stream off?  To me, it's just a duplicate of the camera roll and creates confusion for me.  What is the benefit of photo stream and couldn't I share pics that are on my camera roll? 

3)  Doesn't photo stream go away after one month?  I have pictures in there for quite a long time.  Still a little confused about why I even want or need photo stream. 

Thanks.