with the max adjusters, you really can't get the chains too tight. when you put the chain back on, and pulled up on the adjuster, did you have the tires off the ground? if not you didn't get the chain adjusted properly. a common mistake... jack it up, roll tires in opposite directions so the side of chain without the adjuster is tight (i use my knees to hold the tires while doing this), then move the adjuster to take the slack out of the chain. there are several possible problems. a bent axle, or sprocket. sprockets not aligned properly, adjuster not aligned with sprockets (if the chain is pulling the adjuster away from the frame rail, it will eventually pop the adjuster loose), your chains might just be worn out. your adjuster may also be worn. there are serrated teeth that can become worn and the adjusters won't hold anymore. you may also be missing the spring on the back of the adjuster that holds it tight to the frame. you would probably be best to pull the engine and get a look at everything. if the adjuster is worn out you can get a new one from RI (i think they are about $45 each) if you want to keep riding while you wait for the new adjuster, you can wrap a #44 hose clamp around the adjuster to hold it from slipping... takes a little trial and error to get it positioned where it won't be against the chain. it's a serious band-aid fix, and i wouldn't use it for a long term repair, but it would get you by for a week or 2 and also makes a good emergency repair on the trail.
your squeaking at the front is more likely the inner bushings or the brake assembly. try spraying some oil at the inner bushings and see if it goes away. sometime down the road when you have it apart to replace bearings and bushings you will want to add grease fittings to the inner bushings
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