Hi, and welcome to GameDev.net!
I am a complete noob
No problem. You're at the start of a long and difficult, but very rewarding journey. Expect to spend a lot of time learning and practising, and expect to be frustrated and encounter serious difficulties -- if you stick with it however, you'll find it's an amazing experience to solve those problems and produce a working program!
1. Can anyone tell me, step by step, the process of making a game?
As others have suggested, this is a very broad question and there are entire books that still don't completely answer this question, but I'll take a shot at a very brief overview:
You will use a tool (such as Game Maker, Stencyl, or others) or programming language (such as C#, Python, Lua, C++, or many others), to express the logic of your game; essentially telling the computer how the rules of the game work. This requires a lot of practice, and will need extensive testing to ensure you've done so correctly.
You will use assets (sound, graphics, etc.) that you could purchase, have someone else create for you or could create yourself using other software.
The link suggested by Alpha_ProgDes above contains more good information for you.
2. Can you make a full, expansive world (mainly city) in Blender? From what I've seen, it seems very difficult to do so.
Absolutely, although you probably wouldn't. This would be very time consuming and fiddly. A more achievable approach might involve using blender to create parts of (or in some cases whole) buildings, and then put them together programmatically to create your city.
3. Can Sketchup be viably used for gamemaking? I can make and have made really cool things in it.
It's not a particularly commonly used tool, but as long as the licensing terms are acceptable there's no reason you can't use it for your games.
4. What programming language is best for 3D games, in general? I used to have a good knowledge of Python, HTML, BlitzBasic (that was stupid, haha), and a very precursory, basic grasp of Java, but I forgot a good bit of what I knew. Relearning most of it shouldn't be a problem, though.
In general, it doesn't matter. Good quality 3d games can be created in Python, C#, Java, C++, and many other languages. Choose whichever language you're most comfortable with, or if there's a particular engine you'd like to use try one of the supported languages -- you might choose C# or UnityScript if you intending to use Unity3d for example.
5. How much programming knowledge do you need order to make a half-decent game (for scripting, AI, etc.)
You can create relatively simple games pretty early on, but you won't be creating higher quality games until you've had a reasonable amount of practice; you'll need to learn most of the basic concepts, and you'll need to learn what makes good and bad designs. The quality of game you're able to produce will also depend on the quality of assets (art, audio, etc.) that you use -- it's often not the programming but the art that makes the difference between an ugly or beautiful game.
5. Can you define the following terms:
a. Triangulate meshes,
d. Collision models, and
This is probably something you should do further research on for yourself -- try Googling for the terms, or searching on sites like this one. If you still have questions after searching for these yourself ask a more specific question and we'll help you out.
6. Any other key game development words you think I should know?
It's not about learning words, but understanding concepts. Research as you go, and ask us to clarify anything you don't properly understand.
7. Can I feasibly make such a game by myself?
It's possible, but a lot of work. You'll need to put in a lot of time and effort to do so. You should almost certainly try making some smaller, simpler games beforehand.