Trouble rear on 300

[ageusaf]

Guys I will say sorry up front in case this is already on the forum somewhere. I looked through what I could but didn't see it.
Just started riding this year. Have a background in street bikes but I am new to dirt. However I have put a lot of time in the woods this year and advanced a lot. I was riding a YZ for the first part of the year and just wanted something with a little more power. Got this 08 300 and noticed it felt uncomfortable to ride. I am still to new to know if something is messed up so I didn't notice it was f'd up. Today went out for what might be the only good day left this year in my part of the country and my friend said my rebound must be off on the rear. I did some hill climbing and trail riding and was pushing it hard(for me) and at one point had to get off the bike to stretch and lay down to stretch out my back. He noticed I was unusually fatigued for the amount of time we spent riding. We went to adjust the rebound because it was returning to full extension to where it sounded as if it was topping out hard and we noticed that the screw on the side that should be the rebound only had 3 clicks before it would either be loose or bottom out.
It also is leaking fluid on the rear. Maybe you guys can educate me. I am trying to learn about this bike and bikes in general.
Thanks in advance.

Hollis