Noob questions about Python

[Ixiaus]

I have recently (today) just started learning/playing with Python. So
far I am excited and impressed (coming from PHP background).

I have a few questions regarding Python behavior...

val = 'string'
li = list(val)
print li.reverse()

returns nothing, but,

val = 'string'
li = list(val)
li.reverse()
print li

returns what I want. Why does Python do that?

Also I have been playing around with Binary math and noticed that
Python treats:

val = 00110

as the integer 72 instead of returning 00110, why does Python do that?
(and how can I get around it?)

Grateful for any replies!