since your post count was 1, I know you have not posted on the dongle issue...which would need a separate post if you have not resolved it pls
2) webcams can be tricky beasts.
start with telling us the exact name / model of it pls
if your documents don't tell you and the vendor does not tell you via any website
then another way of starting it off is to look into your /var/log/messages and post the contents of just those line that refer to it
in a terminal run
and post the contents.
3) you can google those details as well.
4) Sorry if its dumbed down but basically it this
your os must have a driver to run it
linux uses a kernel or kernel module(s)
b) the module(s) must be loaded
c) any sound config file must not interfere with it
d) no other sound or action must interfere with it
let me generalise, your sound device, may be considered a microphone ..but if your microphone settings are set to only act as a sound out device....you will never get sound in.
(if you think I am joking I am not)