Hi. Welcome to the forum. I'll try to answer a few of your question.
1. Are any kind of Sig's. allowed on these forums?
Since you have already set up a signature, I'm not sure what you're asking. Obviously, you know signatures are a feature on this forum. Am I missing the point of your question?
2. Is their a ranking system and are their any benefits to them?
One forum here, called Don's Bar and Grill, under Other, can not be accessed until you've attained a certain number of posts. I'm not sure what that number is. Is there a ranking system? Sure, your rank is displayed immediately under your username.
3. Is any kind of question allowed on these fourms as long if they are not against the rules?
Yes, "as long if they are not against the rules."
6. Can you PM people over these forums and if I can how?
While logged on, click on the person's username. That opens a screen where you can initiate a PM.
7. When would it be necessary to modify my message?
Mainly, when you discover an error in your post. Of course, if subject post has already been replied to, the better choice is to acknowledge the error in a new reply, rather than going back at that point and making a correction. And, please, never delete an original post after replies have been posted. I've seen that a few times and it just ruins that discussion topic.
8. How can I make friends on the forums?
I would say, simply through participation, and not being rude, arrogant, and excessively argumentative. For some informal, off-topic, discussions, you might occasionally visit the Off-Topic section.