1.) Who is a newbie and who is a pro is usually a matter of opinion. I, for example, have over 10k battles, so someone just looking at my stats might consider me a "pro". But anyone who actually knows me knows I`m still a total newb when it comes to battles.
2.) If there is Ore or other items above the max price and max posting amount, that is the "Black Market" and is put there by an admin sometimes when there is no other supply in the market. This is to help out the people who really need to the stuff, but is higher priced so that it doesn`t undercut or supersede the postings of a regular player.
3.) Generally the higher PR you are, the more ships/stacks you will see.
4.) I have found that most people in this game are actually pretty nice, if you just take the time to talk to them.
5.) If anyone is cheating in this game, it`s usually because they`re using a bot of some sort to do the research for them. There`s not a whole lot you can do in the market that would be consider cheating, except for posting at 0 for the purpose of "giving" the item to a specific person. If you see ore posted for $2000, it`s probably because someone`s just trying to make quick cash, or because the person is used to playing on a slower server where the ore price is much lower normally, and they don`t realize that they can post higher.