Wa `alaykum As-Salamu waRahmatullahi wa Barakatuh.

 

Jokes will not take someone outside Islam unless they are really meant to belittle Islamic values and make fun of our sacred tenants.

 

So not every joke is a joke that will cause Kufr and it has to be intentionally motivated.

 

Normal jokes about people’s practices are different than Islam itself too.

 

As to your second question, you need to learn. Even if there is no one to teach you, you can access many you tube videos on the net that will help you in that.

 

Islam is built on praying and fasting, so if one says I am a Muslim and practices none of that it means that his claim is not genuine.

 

I hope you can start soon insha Allah.

 

Almighty Allah knows best.