Welcome

! That is a
lot of questions, I'll try to take them on though:
Quote: "1)So, I have the Free edition of DarkBasic Pro, and I am still confused about the difference between the Free and Paid editions of this program.
I got that businesses and educators cannot use the free edition, but I cannot work out any other differences.
I did notice an advertisement at the bottom, but it makes no difference to me, so is that the main difference? does this mean we cannot sell games(or programs) made with it(I don't intend to anyway)?"
According to the download page, "the only difference is that this version is supported by advertisements." So you may sell your games.
Quote: "2)Where can I find some good 3D models of characters, some objects and maybe terrain I can use for non-3D projects(I don't mind including credits)?"
The Game Creator Store has a large quantity of models, and a decent amount of them are free. You can also look on the 3D Chat board, it's a little harder to find things but you'll find a lot of free stuff there too.
Quote: "3)What is the best free Terrain editor for DarkBasic Pro, and does i include instructions on adding the world into DBP(I tried one called 'World', but I always get a File Not Found error when running the game, even though all the paths are correct, I even tried the complete paths, starting with 'C:\' and everything)?"
Search the forum for Tersculpt and/or Magic World. Those are designed for making DBP terrains. You can also use pretty much any 3D Modeling Program, though it might take a little more work to get them into DarkBASIC (I recommend Blender).
Quote: "4)Where is the best place to start learning how to make 3D adventure games, and things like AI control, weapons, health, GUI's and menu's?"
Find the Newcomer's Corner, then find the sticky at the top that says Tutorials Thread.
Quote: "5)Am I insane to be doing this with no knowledge of DBPro(I have some programming experience, some is even with BASIC)?"
Depends on what you're doing. Really, though, every single person here started with no knowledge of DB (even the guy who made
this. And yes, you need to play that

). If you have enough time to play with it, you'll get better and better. I started using DBP...oh...five years ago with absolutely zilch programming experience, and now here I am writing pathfinding algoriths for OpenFPS

.
Quote: "6)This is not a question, but to get the best ideas on help, it may be good to explain my game to you: [snip]
So, because there is 5 different ages in time, it will probably be hard to find models(or make models) and terrains for every one."
I'd like to think it would be easier, because you can use many more models you come across rather than having to filter out ones that don't fit the setting.
Quote: "7)Have you got any advice about this game? maybe feature ideas, somethings that you think I should avoid?"
To get a grasp on DBP's syntax, we usually recommend you start with something simple, like Pong. DBP may as well be designed for RPGs, though, so if you want to jump right into your game, just take it a step at a time. Start with loading a character model and making a floor (just a box object or something), then write in some controls to move the character around, then maybe some obstacle boxes with collision, etc. Tutorials should give you a better idea of how to do this.
Note that you'll probably end up doing a full rewrite of the game anyway when you realize how much you really didn't know back then...now...later...gah.
Quote: "8)If I cannot find models, I will want to try and make them, and I heard Blender was the best free 3D modeling software.
So, where is a good place to learn how to use this?"
Don't forget about Google:
http://en.wikibooks.org/wiki/Blender_3D:_Noob_to_Pro
Quote: "9)I doubt there will be, but does anyone want to help(worth a try )"
Sorry
Quote: "10)What would be an estimate to how long this might take?"
Soulhunter took three years. I think it's comparable to this.
Quote: "11)How often should I backup my work(worth asking, or so I think anyway. I have an external to back it up onto)"
Whenever you finish a few hours of marathon coding.
Quote: "12)Is there another forum I should ask more questions as I get into the development, or should I ask in this thread(by forums, I mean the sections on TGC, not different sites, unless you want to suggest some sites)"
You probably want to make new threads in the DBP Newcomer's Corner.
Quote: "13)If I were to get some money, and buy an FPSC model pack, can I use them in Dark Basic Pro, or is there better model packs designed for Dark Basic Pro?"
They'll work fine in DBP (FPSC is actually made in DBP).
Quote: "14)When I get money, what are the best addons to buy for Dark Basic Pro(like tools and such, made by TGC?)"
Buy the DarkGame Studio package. That's basically everything you will ever ever need (except Blender...but that's free anyway

).
Good luck! (ow my fingers)