2015 Sportsman 850 – Have a few questions-HELP! NEW HERE

Hi looking for someone to answer a few questions I have

First time owning my own atv so work with me here lol

1. I’m sure it shouldn’t do this but I’m able to shift between gears with out holding any brake?

2. While slowing down I hear a knock come from the rear is that normal?

3. So I have a brake pad showing half way underneath the caliper on one of the front wheels its also squeaking

4. There is a small tube hanging from underneath the front end with a black hose coupler on the end is that for the over flow drain?

5. I’m installing strobe lights in the rear can I wire the power straight to the battery (of course with a fuse in between)?

6. When should I have the first service done I was told @ 50hrs is that correct?