You didn't mention your distro, so my answer may be vague and confusing. Distros have different tools for configuring networks and such and I can't read minds yet.
The two files that need changing are /etc/hostname
which should contain one line with your hostname, and /etc/hosts
for your networking. Here are mine for your perusal.
# Redhat 7.3 Celeron 850 box tinwhistle /etc/hosts file
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 tinwhistle localhost.localdomain localhost
The bash prompt is certainly customizable.
From a great resourse, the good old Google search hits