What is the difference between "is there any" and "are there any"? Are these sentences all correct? - Is there any update? - Are there any updates? - If there is any problem, please let me know. - If there are any questions, please let me know. If they are all correct, what is the difference? Thanks!

Is it too hard, in the same time two foreign languages to learn? As everyone in China, I have been learning English since primary school. We learn many grammar, read, write and also speak. I was not a excellent student in English class. But at least I can understand simple English, and make small talk. Since I started to learn German.... I have made many mistakes. For example, write a comma in attributive clauses after "who","where"etc. When I talk with some English speaking guys. I can understand what they say. But I can not talk. There are only German words in my brain!! I wonder if you also have this problem. Sometimes it is also funny. One time in Paris my friend wanted to buy something in Apotheke and she didn't know its name in English. Then she asked: Can you German speak? She putted the verb in the end of clause! Since this June I got a new job and a very good job. And... my new chief comes from a town near by London. I know I have to improve my English now and especially British English.