No, not at the moment.
Yes. To use EAP-TTLS, only small changes to the configuration used in this document are required. To use EAP-TLS, client certificates must be used as well.
Yes. Windows XP SP1/Windows 2000 SP3 has support for PEAP MSCHAPv2 (used in this document). A Windows HOWTO can be found here: FreeRADIUS/WinXP Authentication Setup
Yes. FreeRADIUS can authenticate users from AD by using "ntlm_auth".