I am not sure about bridges but for 350 access points, if you upgrade to latest firmware -12.3(7)JA- you should be able to use WPA (TKIP). And if you are using Cisco Client Adapters, also download latest Installer on laptops with latest ACU version which will support WPA.
For upgrading 350 access point using tftp server, use the following CLI command at previlige mode:
Archive download-sw /overwrite /force-reload tftp://ip address of PC running TFTP service /Name of the image of 12.3(7)JA with extension tar.
We need to explicitly mention the extension as windows does not show up the exntensions if you are copying and pasting the name of the image.