Roomscale does work completely fine with the Oculus. On Vive centric messageboards you'll hear a lot to the contrary though. Oculus+Touch comes with 2 cameras and that worked fine for 95% of the stuff I did, with poor camera placement (like 3 feet off the ground, 3 feet in front of me). I've since mounted them on security camera mounts to the ceiling, and got the 3rd sensor for behind and I have trouble occluding the controllers on purpose to test it out. The stock HDMI/USB cord on the Rift is a little short, but they do sell extensions. Just do your research. The Oculus subreddit has a list of which cables work well and which do not.
I do both seated VR stuff when I'm lazy, or full stand up move around stuff sometimes. My room doesnt have a ton of space, so I have to move stuff around when I want to do roomscale. And yea, the Touch controllers are extremely awesome.
The Rift came in super handy this past week too. My tv I use for my monitor died on me, but I was able to boot up my PC, type my login password blind, wait a min, then put on the Rift and it autolaunches the app and I was in. Between Bigscreen and Virtual Desktop, I could do just about anything on my computer I needed while waiting for new TV to arrive.
As to your other questions, most games do mirror the view to the desktop so people can see. Its program specific, some will do a direct mirror with both screens side by side, others will show one regular window.
As far as best experiences, probably the craziest thing was actually Minecraft. I haven't tried it with the official support, but had a mod someone made before then. Having played countless hours in that game, just seeing it in VR at real scale was intense. A simple 2 block high drop is nothing, but when you look down and see the full 6 feet it trainslates to, its crazy lol.
Other must get games are Raw Data, Dead and Buried, The Unspoken. Robo Recall just came out for free on Rift, but I havent tried it yet. Waiting on Lone Echo as well.
If you have Elite Dangerous, the VR support in that is really fun too. Haven't dug too much into that one yet, its a pretty involved game.
Also Google Earth VR is a must have (and free)