[Tutor] List and comprehension questions

[Smith, Jeff]

I'm getting use to using list iteration and comprehension but still have
some questions.

1. I know to replace
    for i in range(len(list1)):
        do things with list1[i]
with
    for li in list1:
        do things with li
but what if there are two lists that you need to access in sync.  Is
there a simple way to replace
    for i in range(len(list1)):
        do things with list1[i] and list2[i]
with a simple list iteration?

2. I frequently replace list iterations with comprehensions
    list2 = list()
    for li in list1:
        list2.append(somefun(li))
becomes
    list2 = [somefun(li) for li in list1]
but is there a similar way to do this with dictionaries?
    dict2 = dict()
    for (di, dv) in dict1.iteritems():
        dict2[di] = somefun(dv)

3. Last but not least.  I understand the replacement in #2 above is the
proper Pythonic idiom, but what if a list isn't being created.  Is it
considered properly idiomatic to replace
    for li in list1:
        somefun(li)
with
    [somefun(li) for li in list1]

Thanks for the input!
Jeff