2 stripes,
Welcome aboard, congratulations on getting your recent qualification and your job.
You'll find that if the school you are going to work for are worth their salt, they will monitor you closely for the first few months and will be selective about who you fly with, the wx you fly in and who, if anyone, you can send solo.
You have undoubtedly heard the saying that a "little knowledge is a dangerous thing" - well, your suggestion in your posting regarding some PPL's being more dangerous than student's is well founded, as you will soon discover. Don't get me wrong, most PPL's are O.K., but rest assured there will be some who will really 'try it on' with you - they will give you all the bulls**t in the world about how they can do perfect landings when their on their own but can't get close to a good landing when there is an instructor on board. Then they will give you all the bulls**t about where they've been and how experienced they are - some will even suggest that because they have a PPL they are beyond teaching. The main thing you need to be careful of is your inexperience - AS AN INSTRUCTOR. Don't let these few overconfident 'know it all' PPL's take advantage of the fact that you are new to the job.
Well done again, happy flying....