Answer 1

The list constructor takes an iterable (like a string in this case) and returns a list. In your case, this should be roughly equivalent to
def myList(iterator):
tempList = []
for i in iterator:
tempList += [i]
return tempList
Iterating over a string will return it one char at a time, hence a == ['a', 'b', 'c'].

Answer 2

if you want to see what something does, just use a print function
a = 'abc'
a = list(a)
print(a)
print function is also useful for finding bugs. not sure why an if/else is returning the way it is, print what your checking and see if the output is matching your expectations. Things like that