In the early days of my server-career, I had to use lighttpd for RAM-reasons. Over time the limitations of lighttpd were mounting. E.g. no .htaccess-files, no auth with certificates, bad DAViCal integration, inconsistent LDAP-filters. Moreover after some time lighttpd uses up more and more memory.
So for now I'm just using both of them to compare performance and overall ease-of-user.
It is happening. Conventional IPs will run out in less than 2 months from now. After that we might get by another year, by using the IPs we have more efficiently. Still the only long-term solution is to switch to the new IP-protocol version 6.
I'm proud to announce that since today the snapdragon-servers are fully IPv6-ready. That means webserver, mailserver and IMAP. You shouldn't notice any change, since IPv4 is still on as well.
If you would like to see whether you're viewing an v4 or v6-address, you could install this Firefox-plugin or start Chrome with the option --prefer-family=IPv6 or simply browse to the IPv6-version of Google.
If you're not sure how to configure the Email Client of your choice, see here.
Officially recommended clients: Apple Mail, Outlook 2010, Thunderbird