I need to setup a proxy which only has access to a few sites. So it looks like I need squid for the proxy server. Is that all I need or do I need extra security as well?

What other things do you recommend setting up with squid to make sure nobody abuses the network. Outgoing I simply want someone to allow to one site and the rest closed so there doesn't seem to be a security risk in there.

Also if I suppose I have to give my IPaddress to him so then I want him only to use squid. Close all ports on my firewall except for the squid port for the time I'm on vacation?

Then I also don't want any incoming connection except for the site I mentioned above. Is that doable simply with squid or the firewall.

Also I saw a webmin squid module would it be okay if I used it to set it up. I know it's often better writing everything yourself but I'm not sure how much time I have.

Did I think of everything now to have my PC completely locked off except for having a proxy that allows someone or a few different persons to connect to one site only and take care for things while I'm away?

you can configure your iptables to only allow outbound connections to a couple of IPs or hostnames.

So I have to setup squid normally and then iptables fixes the rest? I know I can do it for me logging in but if someone else proxies via my connection.

Thanks for the help do far!