sign language, mostly
No, most Autistic children won't learn ASL.Although there are Autistic children who may be non-verbal or deaf so will learn ASL as a means of communication, not all Autistic people need to use sign language to communicate. Also of course not all Autistic people are American so will learn different languages.
Well, I don't know about other Autistic people but the only cards I use are credit cards for my shopping! You'd have to be more specific as to what sort of cards you're talking about, you may mean ID cards or some Autistic people have cards to communicate.
Autism Spectrum Disorder is a neurological condition, autistic people are born autistic - we do not know why people are autistic.
You can hear Autistic people simply by listening to them - whether they talk verbally or communicate via other means. The organisation Autism Speaks has the tagline 'It's time to listen' but they refuse to listen to autistic people...you can't hear unless you listen, and that's when problems arise with people seeking to 'help' autistic people when they don't know what autistic people need or want.
Firstly, it's offensive for you to imply that autistic people are abnormal - autistic people are different to neurotypical people, not less than. A person is born autistic, it is not something that happens to 'normal' people or something that you turn into, you are always autistic.
No, not all Autistic children are savants. Many Savants are Autistic, but most Autistic people are as normal as Neurotypical people with no particularly special talents.
No, not all autistic people lack a sense of humour. There is a saying in the autism community: once you've met one autistic person...you've met one autistic person. autistic people are as different and varied as neurotypical people.
You can recognise that some Autistic people cannot speak or find it difficult to talk face-to-face or via telephone, thus allowing them the option to also communicate ideas via email or letter. Be very clear about what information you're seeking from Autistic people, asking a question may not be enough if the Autistic person doesn't understand what information you're seeking from them.
Employers do hire Autistic people, however normally when they do they don't realize that the person is Autistic. There is a lot of prejudice against Autistic people so even in areas where there are discrimination laws in place Autistic people often cannot find work, Autistic people normally have to hide their Autism from employers to avoid facing discrimination.
Your autistic child may not recognise their name as their name. Many autistic people are disconnected from how they are percieved by others, not all Autistic people accept the name given to them as representitive of them.
Some people with autism may not speak at all, but that doesn't mean they have nothing to say. They can learn to communicate by signing. Or even using a computer app. Hearing people can sign even if they can't communicate with words. Or some might learn how to type on a computer to communicate.
No, not all autistic people act the same - autistic people are as different and varied as neurotypical people. Like with neurotypical people all autistic people will share common traits, but once you meet one autistic person then you've met one autistic person...we're all very different.