Couple of small additions.
On Gum shields, I believe they are the most important safety equipment on the Rugby pitch. I can't quote much regarding concussion, but I know you are not allowed take the pitch without a gumshield at youth or senior level over here (Ireland). Plus they protect your teeth in a contact situation. I learned tat the expense of the integrity of one of my bottom incisors. Big chip.
If they make you gag, trim the ends and refit untill they don't, shouldn't take too much off them and should still keep your molars apart as your jaw doesn't really bend.
One little conditioning exercise I used to hate was called "up and downs" or "Up, out and down" for Backs.
Sprint a distance (e.g. 22 to halfway line or between tram tracks.) plant turn and sprawl.
Then press up and sprint off back to the other line. Bit like a burpee but with a sprint instead of a jump.
Its a roast and mimics the picking yourself up after a ruck/maul or tackle and getting to the next breakdown. "Up out and down" involves a longer sprint.
Legend has it that the great Micheal Jones did 100 up and downs a day as conditioning.
Could be nonsense but its a good story, and he reinvented the Openside flanker position.
On learning to fall, you can teach someone to Knee>hip>Shoulder but that only helps if they are taken round the hips or knee, or if they are moving forward.
This is not a big use if you get smashed.
And there are other ways to recycle ball out of contact, e.g, between the legs, which accommodate a drive more but can be a bit more risky if you don't know what your are doing.