I have a 2002 Toyota camry and i just installed new brakes. its been about a week since i put them on and they squeak when i first hit them after doing between 35-50 mph. what is it? and also when i turn my wheel from a stand still i hear a knock going in both directions. i think its the cv joints but im not sure

The click or knock may be the cv axle starting to go out after they get worse they will click as turning if they are fine then may be a ball joint or bushing. the brakes get vibration and the back side of pads need a application of anti squeal compound which should of been in the brake shoe box if not then buy some and take them back off and put some on back of pads. Of course this is if the brake job was done correctly or in the case metallic shoes are used then they can do this at first or when cold.

what can you recommend for a good place to buy polyurethane bushings for the front end? is it possible to check the cv joints without taking them out of the car? and do i put the anti squeal compound on the brake pad itself or on the back side?

Yes the back of brake pad. RockAuto.com, I do not believe a check or in the case of repacking cv's is worthwhile, as they get worse you will know it as with every turn at slower speeds at first then higher speeds and more clicking as they get worse will be present until they click while driving without turning at which point they can fall out and do damage and /or cause a wreck as the tire will lay down on the ground, so if they continue to click ever more often and click longer then the pop here and there they started with then before they get to far gone have them replaced as the Camry will last long enough to wear out another set of CV Axles.

P.S. if you do end up putting in new cv's also do the front wheel hub bearings as they will go out before the new set of cv's do and you will end up pulling it all back apart to put bearings in. they have to be pressed in so a shop will need to do this unless you have a press on hand.

The knock you hear may be a control arm bushing or ball joint or sway bar bushings too, really look at all suspension parts.

Back of brake pad not on the surface that comes in contact with disc and on each pad on the front. And RockAuto.com is my choice it is cheaper then local places, if you do not need next day then the standard shipping will be fine as that is what do everything has made it here with-in 2 days. Give yourself some time to see how to use the site its different then most but after you see how it works is much faster/better IMO and also cheaper.

brake pad installation was incorrect, could be the pads are loose in the caliper bracket..