Loose Wheel & Rubbing Rotors
 

Hey all, mildly new to the mountain biking scene... anyways here's the story... I bought a Trek 8000 at the beginning of the season ahve been riding it alot and take good care of it, clean it after every ride etc... etc... I bought a book 'Mountain Bike Maintenance' and have been following it and using tips and tricks... well the past few rides i have had a problem with my the rotors rubbing a bit (Shimano Deore LW BR-M585) and have used the tricks of pushing pistons back in with butter knife works a lil bit and sometimes... and it rubs EVER so slightly the back one didn't rub until i took off the rear tire to clean the cassete and rear derailleur a lil better, as well as taking out the pads and cleaning the pistons... it doesn't make a noise but rubs slightly, same as front... sometimes with front it rubs more and when i spin the front tire it doesn't spin freely after refitting the front tire (I have a fork mount Bicycle rack, so the front wheel is on and off quite frequently!) it will be more like the back spinning quite nicely and not making any noise but rubbing ever soo slightly... its really just an annoyance because i spent alot of money on the bike and wouldn't mind things working perfectly (might be alot to ask) 2nd problem was an occurence i had tonite on the trail... i hit a couple bumps and then my front brake started to rub and was whiney, nothing i thought cuz it had rained all day and trails where quite muddy and wet... i pumped front brake couple times and rubbing went away... then i hit a couple more bumps and noticed that my front wheel had come loose... not like the clasp hadn't opened (not that i know of; but it had loosened) and there was a lil bit of grey liquid like stuff coming front around the skewer/hub on each side (dunno what it was could have been water and mix of metal shaving from the skewer rubbing on the fork loose...?) anyways wondering what the grey stuff might have been and what might have caused it to come loose, it was around 10km into the 12km trail and we were riding faster than we usually do... anyways any help with these two problems would be GREATLY appreciated!
Newbie-Weekend-Warrior