Balancing single host traffic & Persistent WAN usage

[v.smaldino]

Hi all,
i need to force all the web traffic of my school to go through a squid proxy, but i also need to balance between my 2 xDSL connections, then i'm planning to use an external squid box connected on the LAN side and use the pfSense as balancer.
I searched the web and the forum but i didn't find any information about these 2 matters:

1. Does pfSense balance correctly using the 2 WANs even if the traffic comes from a single host (the squid host)?
2. Does pfSense 2.3 "remember" (without sticky flag) the WAN used for a particular destination in order to avoid the "Session Expired" problem when accessing some Web sites requiring authentication?

Many thanks
V