[Django]-HAProxy load balancer in front of Django instances

As far as I know, HAProxy doesn’t do caching. For that you want something like Squid.

As far as treating /static/ seperately, you can set up your HAProxy config to redirect any URLs matching a pattern to another backend cluster:

frontend my_website *:80
    mode http
    acl static url_beg /static/
    use_backend my_static_proxy if static
    default_backend my_django_server

You might want to try varnish instead of squid. It’s much more flexible and has a much newer design, you should read
http://www.varnish-cache.org/trac/wiki/ArchitectNotes