[General Questions and Answers] Product F(RED):
So my questions are:

What role does an SD card have in the Rooting processes and root related things? Is it necessary? What are the advantages of having an SD on the device?

Nothing; the advice about the One just meant that people who root and ROM their devices tend to horde a lot of phone-related files, so expandable storage is a plus since it allows you to cost-effectively add storage as needed. As for advantages? Being able to add storage as you need it, for cheap, and the ability to seamlessly move your files from phone to phone or computer easily. Plus, apps require internal storage, so another plus of having external storage is that you can put all of your media and other files on external storage to save app space.

Can any of the roles an SD card has be worked around without one?

Sort of; both phones (One and S4) support USB OTG. It's a cheap, $2 cable on eBay that's a microUSB adapter on side (goes into the charger port on your phone) and a full-sized USB port on the other. It lets you plug in flash drives, keyboards, mice, etc. There's also this: http://www.kickstarter.com/projects/andyfei/mini-microsd-reader-for-android-smartphones-and-ta

Can I have my backups backed up to the cloud or other method in which they can be quickly restored, like on my X2 with the SD card?

If by backups you mean Titanium Backup, yes. Titanium Backup has a native export to cloud option that supports Google Drive, Dropbox, and other providers. If you mean Nandroids (full device backups), just copy them off your phone to your computer. They're saved in a folder on either your SD card or internal storage (guessing your SD card on your Droid X2). I don't recommend at all restoring app backups from two different devices, let alone two completely different versions of Android. It's guaranteed to screw up your ROM in one way or another. It's fine to restore an app to a different device/version of Android, but not the data with it.

Why do the reviewers stay to stay clear of devices without SD card slots?

A few reasons, though none of them have to do with the ability to root:

- If your phone dies (completely, due to damage or just having a bad unit), the data is pretty much gone and unrecoverable. If you were using a microSD card, you could have just pulled it out of the phone and called it a day.

- You can expand the storage for cheap; one of the biggest flaws of the iPhone is that going from 16GB to 32GB costs $100. A 16GB microSD card is like, what, $10? Nuff said.

- Apps can only be installed to internal storage (unless you use some root apps that are a pain in the butt). If you offload all your media (photos, music, videos, etc) to your external storage, you can have room for all your apps. Remember that games are starting to take up over a gigabyte each in some cases. Grand Theft Auto: Vice City, Need For Speed: Most Wanted, Asphalt 7, etc.

Should I get the One, and now that I think of it, should have I got my Nexus 7 since I'm a rooter and might change ROMs/have to factory reset?

It depends on your preferences. The One is a great phone in itself; it depends on you whether or not the lack of microSD card slot is a deal-breaker. It won't affect your ability to root the phone, but consider the answers to your questions that I gave you (I'm not swaying you from or towards it). The Nexus 7 is a great tablet; again, having a microSD card slot has nothing to do with the ability to root your device.