How many arguments does the insert method takes at a time?

Answer 1

Two - the index and the object to be inserted there. That moves all elements "to the right" by +1 position in the index count.

Answer 2

https://docs.python.org/3/tutorial/datastructures.html
Most languages have some online documentation, and it's good to get used to using them - it's impossible to remember all the methods you need!
There's also an append(x) method if you want to just add something to a list