IPv6 and Watchguard Firewalls

Hey guys,

So, I'm planning to start implementing IPv6 on my networks and I'm looking for a few pointers.

I have two coax connections from Comcast, one gigabit connection with no statics, DHCP and one 100 Megabit connection with a 5 IP block of IPv4 statics and and a /56 IPv6 block.

My networks are schools and I have IPv4 setup right now only with IPv6 turned off. Staff networks are routed out the 100 Megabit connection and Students are routed out the gigabit connection. The reason for this is that when using Comcast's RIP'ed static block with a large number of student devices, we found that the modem would just die routing all of that, so we put in a second modem that is simply bridged and does a single DHCP'ed IPv4 address to the firewall. Apparently, with the way that Comcast does IPv4 static assignments, the modem itself does quite a bit of routing and all of the TCP connections that were happening would REALLY bog it down where it would be unresponsive with 300-500 devices online at once.

Now, I have a IPv6 /64 delegation from Comcast, but I'm not entirely sure how I use it. I'm very new to IPv6, so if this seems like a stupid question, its because I still find IPv6 a bit confusing, as I'm used to the IPv4 and NAT world of yore.

1. How do I had off the IPv6 /64 block to my student's devices and have their gateway be my Watchguard firewall for web filtering?

2. What ICMP protocols do I need to allow for IPv6 to work? I know there are a few that are required in IPv6.

3. Any other pointers on setting something like this up?