You need to call the airline your flying with or check with a travel agent they should tell you each one is different

max of 32kg this is because of safety regulations for their staff...

no staff are supposed to lift anything above that weight...

the last time i checked, intercontinental flights, you are allowed up to two bags, and trans atlantic, up to 25 kg in economy...
within the states its usually one / two bags dependent on airlines etc...

As another answerer said, you need to call the individual airline and ask, or check any FAQs they may have on-line ... but in general I have found that US airlines on domestic flights tend to allow 2 checked bags per passenger of up to 50lb per bag. Some airlines may limit you to 40lb per bag.

This is not a _hard_ limit. It is the limit for luggage without extra charges. You may be allowed up to around 70lb if you are prepared to pay overweight luggage charges. This could be $50/100 per overweight bag.

There may be weight limits for carry-on bags too, in theory, but in practise I have /never/ had a US airline check the weight of my checked luggage. I have had non-US airlines in Europe check the weight of my carry-on. That was a huge pain.

When I worked for the airline you were could have 3 bags without a fee. You could check in all 3 and have no carry on, or check in two carry one, or check in one carry on two. No bag could be more then 70lbs and the total bags checked couldn't be over 150. If you went over any there was a charge of $70. Fees are different from airline to airline and its been 3 years since I worked there. So like I said give your airline a call

Every airline is different. I just flew with a 50 lb limit. But you could have 2 bags. Check the website of your airline.