which types of files we can access?

Answer 1

You can open all files. There are 2 modes of file opening. You can open file as text file. In that mode you read and write strings. In proper encoding. UTF-8 for example. Another mode is byte mode. In that mode you read and write raw bytes.

Answer 2

All of them. Though only some of them will be in a format you can read... conventionally. hehe

Answer 3

all types.