Heater core
#3
???
Not really,some have suggested taking a plasma cutter to the fire wall and creating a trap door from the firewall,but with all that has to be shifted and moved around you'll just have no choice but to drop the dash.Besides when I did mine it was a good time to clean the backside,dust,dirt and other stuff that kind of makes you WTF....If you find a short cut let us know.Do have a extra set of hands if possible it can be a dirty job and labor entencive,and bandaids....