X-cross mountain biker-brakes

You asked about releasing the rear brake but posted a picture of the rear derailleur. Clarification would be very helpful.

only if you have a resevoir with that fluid in it there should be a bleeder valve in the caliper

Any search engine would take "remove rear bicycle tire" and produce many good answers. Involvement of Fixya experts is an unnecessary and delaying step.

http://www.parktool.com/blog/repair-help/shift-levers-shifters

It probably is working right. 8 clicks gives you 9 positions.

http://www.parktool.com/blog/repair-help/chain-installation-derailleur-bikes

take it to a bike shop and have them replace the wheel bearings. i just had to have that done to mine

Have a look at Repair How Tos on this site:http://www.parktool.com/repair/byregion.asp?catid=53 Good pictures and explanations.

You need spare olives (the brass ones are best) buy on Chainreactioncycles.com, measure your hose and allow for bad cut first time so add a Cm to measurement you can cut away just make sure that you use really sharp cutter (I use craftknife) place hose on non slip surface and cut cleanly, push on olive and reattach and tighten

You can use a good old metal screw for this. If the back of the screw hole is open, just get a coarse threaded metal screw that is approximately the fight diameter and use it. Or, if you want to be precise (and far more safe), take the screw you do have to a hardware store, or a fastener supplier, and have them set you up with the correct screw. i do not know where you live, but if you Google map "hardware store" you should be able to find one pretty close by.