Can a pix 501 split traffic between 2 routers

currently the line speed is about 1.6 mb and the mail is hosted internally lotus notesserver. we will be using an external hosting company and once we move our mail to the hosting company using microsft exchange the existing line may not be adiquate so may need another line.
the routers will be provided by the ISP.

can I split the traffic so all traffic except mail will route from the pix via router A to the internet or the hosting company and all smtp traffic will route from the pix via router B to the hosting companys mail server

secondly if a pix or asa can do this will it also support QOS and actually load balance the traffic so both mail and other traffic can go down both lines ??

can upgrade to asa if this works