Quark's

So, I have some questions about formatting on this site:

1. How can I make "sub-lists". Kinda like a "1a,1b,1c". For instance, an Idea I have involves pros and cons. I want to make a list of that idea, with a sub-list of "pro" and "con", and bellow them a sub-list of the different pro's and cons
2. Can you make tables (I can't figure out if you can from what's on the "format help" page, I found it confusing)
3. what is the "URL" field at the top of this post for?
4. How do I make "minor separations", where you have multiple paragraphs, then a paragraph with more white-space between it, but not like a header or a line. It's related enough that I want it connect, but separate enough that I want some separation
5. How can I make Paragraphs have indents? (I know they aren't needed grammatically anymore, but in some cases, a paragraph just doesn't seem "right" without an indent...

I do have some more questions, but I forgot them right now...

Thanks in advance!