HELP! Basic Forum Use Q's

I have a few questions about using the forums.

1.) I recently posted a thread about my new kill marks. At first there were no problems but when I cam back to it today to update the status of the project I found that the "Edit" button was gone! I cannot change my thread! why is this? is there some limit on the amount of time after initial posting that you can edit? if so, why? It is incredibly inconvenient!

2.) what do mentions do? why are they here and what are they used for?

3.) what do the credit and level system do? What are credits used for? what does you level mean?

4.) what does the activity percentage do? How come is never goes up for me even though I am very active? what is its significance?

5.) I know that a sticky thread appears at the top of search results and section pages but what exactly does it do? I had someone suggest that my thread be made sticky? what requirements are there for being a sticky thread?


Thanks for helping in advance. I know these are very newbie questions and there is probably already a thread about them but I could not find answers on the site. If there is a thread it should definitely be sticky so people like me can find it better when we have these FAQs.