1) Yep, as many folks have used that guide and similar ones of late (I found some info in that one as well as several others - there isn't just one single guide out there that really provides enough info itself so cull info from all sources to learn the most you can).
2) With SDR# and the Frequency Manager + Scanner plugin (note that this is a totally separate and more feature-laden plugin than the very simplistic one that comes included with SDR# itself) you can create scan groups (by name) and then assign specific frequencies to be included in that particular group after which you can "scan" the group which will make SDR# tune them jumping from frequency to frequency, with potential delays put in place, specific signal strength(s) to cause it to stop on a frequency, and other aspects.
3) There's no way to know till you give it a shot. There are reports from people that dedicate such hardware to the task of being SDR-specific machines and some have good luck, some don't, but as just stated, you'll just have to hook everything up and install or use whatever software is required (including the Zadig drivers for the RTL stick(s) installed properly) and then give it a run and see how it works out. Running SDR# (that's my app of choice, but don't limit yourself to just that one as there are several others: SDR-Radio (gotta love that redundant acronym), RTL-SDR, HDSDR, GNU Radio, and so on and yes some of those are Linux-based software.
Here's the biggest thing I can say overall: if you think you're gonna hook up a "cheap USB TV tuner" and do everything your handheld or mobile scanner does by design, well, you're going to be somewhat disappointed. You can do a lot with SDR at this time, but one could still consider the entire SDR concept as somewhat new and still limited by the lack of software to do most everything that modern scanners can do.
The other issue is that there's no one single app that can do everything - you typically are required to use several apps at the same time to get a task done. You can use Unitrunker nowadays (as of preview version 1.0.27.10) to control 2 RTL sticks (or some other hardware): one for the control channel and to be decoded which then passes the info to the second stick for tuning the voice channels. I personally did get that setup working but I had a lot of interference for some reason on the voice channels
only when using Unitrunker as the controller for both RTL sticks. I've since moved to a setup where I tune the control channel with Unitrunker and then feed the voice channel info to SDR# by way of the trunking plugin and it works much better for me.
And that's just analog: if you want to listen in on digital comms like P25, DMR/MOTOTRBO, NXDN, or something else then you end up adding yet another program in the mix - either DSD (the original version) or the newest application known as DSD+ (while their names are similar, they are
not the same programs, not by the same people either, so DSD+ isn't just a new improved DSD by the same person or persons). You add one of those apps into the audio signal path (baseband audio) and they will decode the digital data streams into audio aka the speech you're hoping to monitor. A lot of folks use one of the virtual audio cable drivers also that allows you to easily pass audio to the programs through the Windows mixer; I use one called
VB-Audio Virtual Cable myself, donationware, and it works without issues and for me hasn't required any configuration at all - I installed it and voila, it just worked.
Last last tip: if you intend to do this, you're going to need a better antenna than the el cheapo practically useless one that comes with these RTL sticks, the tiny little 4-5" ones that are nothing to write home about. Get a pigtail with your RTL stick or order one from an eBay or Amazon reseller that allows you to hook up a proper antenna: for my 2 RTL sticks, I have 6" MCX (on the RTL stick side) to BNC female pigtails and haven't had any issues with them since I got them. A must-have thing if you wish to get into using RTL sticks, most definitely.