The downloaded 64 bit installer for REAPER is a whopping 11 MB. This is NOT because it is a limited software. It is because REAPER is strictly MEAT with a small side of POTATOES. There are no samples included. No fancy face graphic plugins, or anything else besides a lean and mean DAW with a small selection of extremely useful staple FX like EQs, multiband compressor, compressor, Etc.
At first I wrote the FX that come with REAPER totally off, because they are deceptively plain looking, but after seeing user after user praise them, I finally started checking them out more in depth. Turns out they are actually very high quality plugins and will perform extremely well for most of your essential needs. Note that the screen cap I posted on the first page of this thread is using ReaEQ on every track, plus the master. I'm also using ReaXcomp (the multiband compressor) on my kick, snare, and toms. I have plenty of other EQs, and multiband compressors, but those are my go to tools because they do exactly what I need them to do.
The way folders work as busses has been mentioned a couple times. I personally love the way a folder is a bus, but if you really want a folder to just be a folder, all it takes is one click of the item "Master Send" on the Sends/Receives panel of that folder.
If you disable a folder as a bus, and then want to create your own bus, you would simply designate a track to be the bus, and then drag-n-drop from the "Sends/Receives" buttons of the tracks you want to send, over to the track you designated as the bus.
I think of it as pulling a virtual patch cable, and this technique is also how you lace other things up in REAPER, like sending from a track to another track or bus for routing midi or audio. It is extremely efficient to use and quite fast. For example, lets say I put a reverb on a track and want to send several things to it from other tracks. I would just drag from the "Sends/Receives" button of the tracks I want reverb on to the track with the reverb. Once you drop, you will get a popup panel that lets you adjust the level you are sending if needed. This panel also lets you do things like assign a different channel than the default for midi or audio, which is useful when sending a bunch of midi tracks to a single multi-timbral instrument like Kontakt. For audio, changing the default channel from the normal 1-2 stereo to say, 3-4 lets you easily send down a pipe that will be used not for what you hear, but for what will be used as detection on a plugin, as is the case for side-chaining. I hope this clears up some of the confusion.
REAPER is simple to use, but only after you get familiar with the paradigm it lives in, which is not like most other DAWs.