Another option is if your provider will forward web requests that come in on the standard HTTP port 80 for your domain to your Arc process listening on a port such as 8080.
I would assume so. I've used Apache's ProxyPass frequently and haven't had a problem. There's no technical reason that I know of that it would be either faster or slower than fastcgi. In both cases Apache is passing on the request to a persistent process. I haven't measured it though.