Squatting & lifting a leg is *usually* associated with different causes. Unless the dog has not learned to lift his leg or is in a position where it is unable to do so.

Squatting is "usually" a medical problem, where as lifting a leg is "usually" a behavior problem.

Not always but usually.

I'd get him to the vets for a urine sample & exam to rule out any types of urinary/bladder infections/stones.
Is his drinking icreased? You may want to do blood work on him to rulke out diabettes, thyroid, cushings etc...

Good luck with him.