1) What is the best way to root a droid, specifically the G2x? Are there differences, advantages, disadvantages of different methods, or do they all lead me to the same place?
Best way to root is to use the superoneclick method. It's beyond easy, it's literally downloading the program, and clicking root. Here is the link.
2) For jailbroken Apple products, there is Cydia. Is there anything similar for Android?
I've never heard of Cydia, but I'm assuming you are asking can you download pirated games/programs? The answer is yes, there are MANY sites you can find on the web, though I'm against pirated games/apps.
3) Is there a difference between a jailbroken iPhone and a rooted Android? Are they functionally similar and are simply two different words for the same outcome, or are they completely different?
Never had an Iphone, so not exactly sure the exact def of jailbroken. Rooting an Android phone will basically give you superuser ability to change anything on the phone you want. It's similar to logging into Windows as an Administrator. It allows you to customize things you normally wouldn't be able to. Benefits are removing bloatware, installing custom roms, removing ads, etc.
4) I would like to create a hotspot using the Android, without necessarily going through T-Mobile. I would like to tether my laptop and iPod Touch to the G2x. What is the best way of accomplishing this?
Yes, there is a way to do this, I just haven't done this. A simple search will pull this up.
5) Is there anything else that you think I need to know before I begin the process of transitioning to Android? Anything that I should expect, keep an eye on, etc?
Once you get all your programs downloaded, I would def invest in Titanium Backup Pro. It will allow you to save all your programs, and if you have to reload a rom, you can just click a button and have all your programs restored. Also, read up on making a "nandroid". This basically will backup your entire rom/programs so if you screw something up, you can restore everything back to the way they were. Do a lot of reading on NVflash. If you plan on putting custom roms on here (which you will def want to), this is the best method to install clockwork. Link is here
Hope this helps
Samsung Galaxy Note 2
"They once made Chuck Norris toilet paper, but it wouldn't take sh!t from anyone"