As for Kazama, you need his passive ability. Whenever he damages an enemy, only one shot is automatically reloaded... Shoot the enemy continuously without killing kazama for as long as possible..( One damage = one bullet load)

for Gloria when someone step on the bomb it bounce him/her back in the air,and that's when you need to do the kill,I only had 1 out 3,(best in doors,or paths when holding eye on it)some ppl are great in putting bomb in annoying places, 😉,Christina can only put 3 sticky bombs at the time on the map,so someone needs to walk on them whilst she far away 25m from it,if you place them 3,and not use them they will stay in place until someone finally walk on them...or not lol,hope that helps;)

does reading not help?