I would never use stop leak in the cooling system, it is well known to clog passages especially smaller ones in the cylinder head and heater core. Please flush the entire cooling system all out to the best of your ability ASAP and it would be a good idea to do a flush again in a month, and maybe even again after that.
I can't offer specific tips and tricks as I never replaced the rad in my 2000 Taurus. The best replacement is a new high quality radiator. If money is tight, you could try using JB Weld if you grind the crack down and roughen up the surface first. It would have to be drained to do that. If the rad hoses are original this would be a good time to replace them with new ones for preventative maintenance. Re-use the spring clamp radiator hose clamps, do not use the cheap worm-screw type clamps that most auto parts stores sell, they are inferior.
The automatic temp control shouldn't affect which rad you have. Most auto parts stores can look up your specific year/make/model/trim/options to get the right part. You could also look online yourself at a place like RockAuto.com
I can't offer specific tips and tricks as I never replaced the rad in my 2000 Taurus. The best replacement is a new high quality radiator. If money is tight, you could try using JB Weld if you grind the crack down and roughen up the surface first. It would have to be drained to do that. If the rad hoses are original this would be a good time to replace them with new ones for preventative maintenance. Re-use the spring clamp radiator hose clamps, do not use the cheap worm-screw type clamps that most auto parts stores sell, they are inferior.
The automatic temp control shouldn't affect which rad you have. Most auto parts stores can look up your specific year/make/model/trim/options to get the right part. You could also look online yourself at a place like RockAuto.com