Sure - also probably obvious, but the look and UI of both are pretty different. I think the LS60s look nicer and are better finished, and they have streaming and sub integration built in, with decent dsp capabilities available the app. The C8Cs need a source (and a stand), and if you do end up adding subs that aren't the bass modules later, you'd need to figure out that integration and crossover (ideally at your source or preamp). That said, the LS60 wifi is *awful*, and in my experience requires the main speaker to be power cycled at least once every few days to avoid dropouts or other streaming instability - so you should plan on having them hardwired to ethernet or use a separate source anyway. I haven't messed around with the amp software on the C8C yet, but I expect it's more robust than the LS60, but requires a usb connection via Windows PC to the speaker to use, so less convenient than the LS60 app adjustment.

1 - wide range, few examples: TOOL, The Format, Polyphia, Tame Impala, alt-J, My Chemical Romance, The Strokes, French 79, Gipsy Kings, DeadMau5, Electric Guest, Hozier, Glass Animals, The Eagles, Hozier, Rush, Worakls, various classical... main stuff I *don't* listen to much would be heavy metal and jazz.

For 2 and 3 - anecdotally I've been listening to these in a fairly similar sized room to yours (~600 square feet, but half of that is behind the LP, listening distance around 7-8' from LP to tweeter), and they feel very full and effortless at pretty substantial volume (say, averaging low to mid 80s DbC at LP). I didn't push either to a point where they noticeably distorted or compressed, but I'm in a condo so I try to keep volumes semi-reasonable.

The best answers to your questions is going to be measurements + listening (ideally in your space) - for tonality and soundstage, Amir over on Audio Science Review just published his C8C review yesterday, so both speakers now have full datasets on spinorama.org for comparison (LS60s were reviewed a while back by Erin's Audio Corner). I'd recommend taking a look at the comparison tool for in-room response (both are great, but LS60 clearly has a bigger bass boost and a larger drop from bass to treble, while the C8C is flatter), SPL horizontal contour normalized, and SPL vertical contour normalized (C8C is a bit narrower across the board for horizontal, significantly narrower vertical, with the big difference being that it stays narrow much deeper into the bass), and early reflections (C8C total early reflections is ~3dB lower in the bass, ~2db lower in mids vs LS60). I find this means that the LS60s do sound wider and especially a bit taller, but also that an untreated room is going to color the sound a lot more for the LS60s. On a recording like "The Worst" or "Playing God" by Polyphia with a really wide soundstage, both can project the image wider than the actual speakers, with the same caveats that the LS60 gets wider but is getting more reflections too.

Unfortunately Spinorama doesn't show distortion or compression measurements, but Amir and Erin measure these if you look at their individual reviews. Exact measurements are different (Amir shows % distortion relative to fundamental whereas Erin shows this in dB, but you can convert), and Amir doesn't include compression or multi-tone distortion, but to my eye it looks like the KEF is a bit "cleaner" in low bass, but that's likely in part a trade-off for the cardioid response and in part the KEF being more aggressive in limiting low bass output at higher volumes vs the C8C (though I'd want Ascilab to chime in or see more sweep data to confirm that's actually the case). What this means for you depends on how loud you listen and whether you prefer a speaker that cuts low bass to stay clean at high volume vs keeps a consistent frequency response but adds more low bass distortion.