HSRP with DSL and T1

Hi,
I have two sites connected through WWW(routerA below) and am trying to
configure HSRP for redundancy at both sites by subscribing
DSL(routerB).

My current layout:
WWW
|
routerA(T1)
|
|
Firewall
|
|
LAN

PLAN for redundancy:
WWW --------------|
| |
routerA(T1) routerB(DSL)
| |
| |
Firewall -------------|
|
|
LAN

I have a couple of questions. I'd appreciate your help.

1. Currently routerA uses public IP. Do I need another two valid public
IPs(one for the additional DSL router and another for virtual IP in
HSRP)?
2. How does the incoming traffic work? Can incoming traffic come
through either routers IP, virtual IP, or active IP?
3. Is there a way to utilize both T1 and DSL without having to put one
in inactive status most of the time?

I hope I provided enough information to clarify my question...:-)..
Thanks,
DW

.