Re: Is this possible?

I want to use a freeradius server for the following purposes:

- grant authorizaton to Cisco switches via LDAP (group membership checking, etc).

Yes.

- make a WIFI with WPA+802.1x via MS IAS/RRAS (the main auth is done by the IAS, so the freeradius acts as client for IAS/RRAS, and the WIFI APs act as radclients for freeradius) - wired 802.1x via MS IAS/RRAS

Yes. Configure realm for IAS server in proxy.conf and freeradius as IAS client. user@realm will then be proxied to IAS.