If cv joint is bad car has a lot of vibration, boots arent torn or leaking, but makes a humming noise. is this cv joint or something else?

you've got a bad axle shaft in the front and possibly a bad bearing in the hub. 4/wheel drive makes the front axle actually work. Theys no real pressure on these shafts when in 2/wheel drive.

A "CLICKING" NOISE WHEN TURNING USUALLY INDICATES A BAD CV JOINT. LOOK AT SIDE MAKING NOISE AT INNER AND OUTER CV RUBBER BOOTS...IF CRACKED OR TORN....PROBABLY NEED NEW CV JOINT

Sounds like a hub bearing a nd a leaking axle seal to me. The two parts are seperate and have nothing to do with the other so it was just a coincidence that you noticed the leak after you heard the hub bearing. Replace the axle seal to stop the leak and then replace the hub bearing assembly to fix the humm because you have to dissassemble all of that to fix the axle leak anyway.

lower control arm / ball joint, had same trouble with my work beater

1. bad tire
2. bad rotor
3. bad axle

check tire first . not cv boot it just a cover for the axle - hold grease - dont let dirt in axle nuckles.under cv boot is the axle joint if boot is torn it lets grease out an dirt in an drys the joint out causing problems....

popping noise when turning is usually caused by worn CV joints. Inspect CV boots for tears. Torn boot will allow dust to get in and cause wear. If boot is torn, replace CV joint or entire shaft (usually easier). If boot is not torn, grab shaft next to each CV joint and see how much movement you can cause in the joint. If one CV moves more than the other three, that one is probably bad.

A clicking noise heard especially while making a turn is most likely a CV (constant Velocity) drive axle(s) that is worn out, and if the CV boots are torn and dirt has been getting into the drive axle CV joint, then replace the CV drive axle assembly and do not have the drive axle re-built or re-booted, especially when you can purchase a complete new CV axle assembly for under $60.00 and here is a link to check one out.

http://www.familycar.com/store/item/Chevrolet_Malibu_Replacement_Axle-Assembly_1997_2003_ARBC507101.html

The out put shaft bearing may have gone bad and the transmission oil is leaking out and running down the CV joint on the out side. The other thing to is check the CV Joint, if it's the inside joint. It will not make any clicking noise, just the out side joint where the wheel hub is and when your making a turns is when it makes the clicking noise. The best thing to do is to jack the car up and make sure you use stands to secure it to make sure the car does not comedown on you. Inspect the CV joint, look for excessive play and oil leak from the transmission if any. Good luck and keep me posted, Oh and don't for get to check your transmission fluid level. 

CV Joint Axle Replacement - How to Repair or Replace

Over time the rubber boots of the CV joints can become cracked, torn, or otherwise compromised. Once moisture and dirt get into a CV joint and grease makes its way out, the CV joints days are numbered. Signs of impending failures are a click-click-clicking or metallic crackling noise while turning and accelerating or a clunking upon deceleration. While one can repack, reboot, and rebuild CV axles, it makes more sense for the average do-it-yourselfer to procure replacement units and swap out the old axles. If a boot is torn or missing, it is possible to save the joint if caught early enough, but usually the damage has already been done. Replacing or servicing the entire CV joint axle assembly may be the smarter move since replacing a boot may involve removing an axle, which may also involve removing half or all of the vehicle's brakes and suspension.

Usually when a CV joint goes bad, it's because the rubber boot has become torn or otherwise open to the elements, and dirt/grit/etc has gotten in there and ruined the joint. If the boots are intact, chances are that the CV joint is OK.

It may be a wheel bearing too - this could be an early sign of it. Audi is known for wheel bearing failures.