So I know I've been doing it sort of wrong all these years, but I never really took the time to understand what "right" looks like. I'm trying to get that done today. Have a few questions:
 
I'll use an orchestral/vocal project as an example. Currently, I have each section (strings,winds, vocals etc.) outputting to its own bus. So I have a Strings bus and a Vocals bus, etc. I use these to adjust the levels of the sections. For the Vocals, let's say I want to add some reverb. I will add the reverb FX to the Vocals bus bin. I understand now that this is not the preferred way to do it, because the entire signal is being processed by the reverb, so I can't adjust the amount of vocal signal that gets the effect. As I understand it, I want to create a Send, and put the reverb in the Send. Which is exactly like the bus, except that it is added in the Sends section of each vocal track instead of in the Output. Right so far?
 
However, I will still want to adjust the TOTAL output volume of the vocals relative to everything else, and for that I DO need an output bus, and I should route all the vocals' Output to that bus. So for the vocals, I now have two Buses, one used as the Send, which contains reverb and maybe other effects,  and another bus that is only used for total output but typically won't contain any effects in its bin. Right?
 
OK, now if I want to adjust the amount of the vocal signal that goes through the send effects, I can adjust it through the Send Level knobs for each vocal track. However, I can also adjust the total volume of that send with its fader. This part gets confusing to me. Say I want to hear the vocal with no effect at all, so (apart from just turning off the Send), I would turn the Send Level for each vocal track all the way down. This way the tracks' outputs are only going to the final volume bus and bypassing the effect send entirely. Conversely, if I want a whole shipload of effect on them, I need to turn the Send Levels way up for each vocal track, and then I can mess with the Send's output fader to adjust the total level of the effect. Is this right? Somehow it seems I'm still missing some concept here. And it seems like a pain to have two knobs just to change the amount of effect I want. Also it seems like a pain to have to adjust the send level individually for each vocal track. 
 
OH WAIT -- Is what I want to do instead to add the effect send to the vocal bus instead of to the Send for each track? That way I only have to turn one Send Level knob (in the vocal bus) to adjust the effect level for the whole track. Aha.... Am I understanding this right? I still would have to adjust two things to change the amount of the effects without changing the total output volume, right?
 
On a related topic, I just learned about the ProChannel EQ effect. I've been putting the Sonitus EQ effect on every track that needs EQ. I'd like to switch to the ProChannel because I can see the graphic display in the console. Any penalty switching over? Will I be using less PC resources because I'm using the ProChannel EQ instead of an added EQ?

Everyone comes up with a system that works for them. There are, as you are finding out, many possibilities to sending a signal hither and yawn. 
 
Myself I don't find much reason to create group busses for every thing. 
I might create a sub mix buss if there are more than 2 of a certain source. LIke 3 back up vocal tracks. But the lead vocal is always direct to master. 
 
I normally make a reverb and a delay buss which is then shared by not only the vocals but other sources too. I control the effect at the channel send. I never touch the effect buss levels. It's always at unity. 
If I do create a sub mix buss then the effect send will be on that buss , not on the individual channels so I can apply amount globally. 
Sending any channel or buss to an effects buss will also add overall gain from those sources so one needs to pay attention to detail. It's part of the craft of mixing, no one said it's simple. 

There is nothing inherently 'wrong' with any of the methods you have described to add reverb to your vocal section, and it sounds as though you have your head around aeh if the options. In the first method you are simply using the wet/dry mix of the reverb plugin itself to adjust the amount of effect that is applied. The advantage of a send from each vocal track is that you have more control, with  the ability to adjust how much effect is applied to each individual vocalist.
 
I understand your joy at discovering the Pro Channe - it is great isn't it! I doubt that there is much difference in processing power. I can't recall whether X3e has the RTA display behind the controls when you enlarge the EQ control panel (by clicking the small arrow at the side of the EQ display in either Track or Console view). That s another great advantage of the Pro Channel over the Sonitus.

Right now I'm doing an church orch & choir project.
 
I send all brass to a brass bus, all woodwinds to a WW bus, all strings, all rhythm, etc. so I can control section volume and reverb sends on a per-section basis. Balance within sections is handled via track automation. I don't do much fancy routing like sidechaining or 'new york compression', at least not for something like this.
 
 
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So here's my bus pane, generally: (-- means the bus has sub-buses)
 
A MAIN -- (Mix EQ, any 'tube' treatment, maybe a multiband comp, limiter)
B    ORCH ---
C       Brass
D       Ww
E       Strings
F       Rhythm (Piano & guitars & EBass)
G       Drums (drum bus compression)
H   CHOIR
I   SOLOISTS (vocal soloists)
J   REVERB (Reverb set at 100% wet, control mix via the send levels from the other buses. Input via send only)
 
 
 
 

I've been a huge fan of SOS magazine .  Here ss an article pertaining o Sends in Sonar techniques section.
 
SOS Sends Article

If you want to hear just the "dry" vocals, mute the reverb bus
If you just want to hear what the reverb sounds like, solo the reverb bus
 
Note that you no longer require a bus to do this - just insert a send to an Aux track, put your reverb on this track.
Set all the sends on your other vocal tracks to the same Aux track

My method: 
1. create two busses, one called Vocals and the other Vocal Reverb
2. add sends to each vocal track to route them to the reverb bus
    now I can vary the amount of reverb on, say, the lead vs. background vocals,
    and I can automate them if necessary
3. route the vocal reverb bus to the vocal bus
    this lets me adjust and automate the vocal volume, including the reverb
4. place a volume automation envelope on the reverb bus so I can automate the
    full reverb mix independently of the vocal bus
 
You can still adjust the dry/wet mix if the reverb is inserted directly into the vocal bus, but
having the reverb 100% wet on its own bus gives you far more flexibility, e.g. effecting
the reverb separately with EQ, compression, panning/pan modulation and chorus.