I can't answer your question accurately without more information. In general wireless changes security requirements by broadening the points of access into the network. For wireless LANs, many offer layer 2 encryption. There is also nothing inhere...
No. I just had a look at the release notes, and it looks like you need Cisco IOS Release 12.1(1)T. http://www.cisco.com/univercd/cc/td/doc/product/iaabu/csvpnc/csvpnrn/vpn11rn.htm