I take exemestane which is similar and moving around / activity is the best thing for painful joints. I am stiff getting up in th emorning or after an extended period sitting down but this wears off quite quickly if I move around. I find running really helps with my mood and my joints, and I try to run most days - not far or fast, but it feels good to get your heart rate up and I don't have any issues with joints then.
I do find that I've had a few more pain issues than I used to - very sore wrist ligaments, sore feet etc but they seem to get bad for a few weeks/months or so and then gradually ease off again.
My oncologist told me that most side effects resolve after 6 months and I certainly feel like things are improving and I am not at 6 months yet.
I think people find different brands make a difference for letrozol in particular so you may be able to experiment with that.
As for drying skin, mine actually seems ok but I tend to use gentle moisturisers and shower gels etc
