1) My Switch 2 joycons fit perfectly.
2) There are some non-slip pads on the inside to keep the joycon 2 from slipping out.
3) a) There are 2 elastic bands included.
3) b) They are meant to wrap around the joycons so that the joycons don't pop out.
3) c) The joycons don't feel like they will pop out. So, the elastic bands will probably end up in the garbage.
4) Pulling on the trigger will press down on the the ZL or ZR buttons.
5) a) I was using these fine in The House of the Dead Remake. It was really fun.
5) b) Other games that look like would be fun to use these grips with are Mad Bullets and Assault ChaingunS KM. I don't have either of these games yet but they look fun.
5) c) The Wii is still better because of the sensor bar though.
I can recommend these joycon grips. They are really fun to use.