This is exactly how I've been playing. But I find most popular music on the TC only goes down as low as middle C (1), and it it is frequently written up to the G above the staff (G5) which is a bit difficult for me at this stage even though I am sounding an octave lower (G4). I follow your fingering from written middle C (1), D (0), E (1-2), F#(2), G(0), but when I get to the next A (written A4, sounding A3), pressing only the first valve is easier to play than pressing 1-3. And to sound B3, I play it with no valves (0). It will sound the same pitch with 1-2 but it seems easier to play with less tubing. I do have a third valve, but I find the C Major Scale plays better with only the first two valves: 1, 0, 1-2, 1, 0, 1, 0, 1. I play G Major Scale 0, 1, 0, 1, 0, 1-2, 2, 0.
As for playing it transposed, the way I understand it was played in Drum Corps, I'm still trying to understand that. You wrote, " Low C (grand staff middle C) on the clef is concert G." If I understand that right, I see middle C written, and I sound G2(with fingering 0). So let's say I want to play Joy to the World, "CBAGFEDCGAABBC." Do I look at those notes on the sheet and sound GF#EDCBAGDEEF#F#G? Or do I get out my pencil and write the bugle part so it is written F#EDCBAGF#CDDF#F#G, and then when I play it, it sounds CBAGFEDCGAABBC? If the latter is true, then I need music that is written for G bugle whether I source it that way or just transpose/rewrite it myself. If the former is true, then I just sound an octave and a perfect fourth lower than what is written.
Sounding an octave lower than written is fine. What are the ramifications of sounding an octave and a perfect fourth lower than written? How does that work in a band? Do I need to compensate for that fourth by transposing the sheet music, or do I still sound ok because the notes are within the harmonic series?
I am not concerned about compatibility with Bb. I am much more likely to be playing solo or with instruments in concert pitch: guitar, bass, keyboard, and vocals (and drums). A fake book is exactly what I'm likely to be looking at. I should get one of those.