Will I be able to use this Broadcom BCM 4352 or other 802.11ac card?
Will I be able to use this Broadcom BCM 4352 card with pfSense?
Failing that, which other 802.11ac PCI-E card could I use?
As far as I have understood, these are the supported Wireless cards: https://docs.google.com/spreadsheet/ccc?key=0AojFUXcbH0ROdHgwYkFHbkRUdV9hVWljVWl5SXkxbFE&hl=en#gid=0
In the list hostap is support is needed to act as a wireless access-point.
Only Wireless-G NICs are supported and some Wireless-N cards may be supported in G-mode. There is no support for N/AC, but it may change with pfSense 2.2 using FreeBSD 10 as far as I have understood.
we haven't gotten to 802.11n yet (it's in pfSense 2.2).
802.11ac: not for a while (measured in years)