domain name registration

ok, well i have two questions,
i am registering a domain name with www.maddogdomains.com
and hosting it with another company.
question is how do the two work together? is it like maddogdomain will register the name for me and provided the info i give them about the webhost redirect traffic to webhost?

and other question is any good/cheap domain name registrar you can recommend?

thanks in advance!