802.11 wireless

Hi,

could someone clear my doubts.

Scenario – wireless security setup

802.1x authentication using PEAP with EAP-MSCHAP V2. Here I know that server
authentication certificate is requried only on RADIUS server for
authenticating the server.

Question 1)
I presume that WPA2 with AES encryption is used for data integrity and
encryption and this is happening only between the access point or switch and
the wireless client. Am I right.
Is there a certificate used for this.

Question 2)
What is reauthentication. Is this happens only with roaming users. If not
Where we can configure reauthentication interval.

thanks