Disconnect the hoses in and out. Then run a garden hose with low pressure through it. Once the soolant is clear the core is flushed.
Buy a kit at Wal-Mart or auto parts comes with adaptors, fittings, and instructions
The heater core is inside the hvac housing behind the dash.
About $600
Yes
The heater core is inside the hvac housing under the dash.
It would be best to disconnect the coolant lines and flush the core after the radiator flush. This will clear any sediment from the core.
I also have a 2000 jeep wrangler. This year has a problem with the heater core plugging up. You can either try to flush it out, or just replace the heater core.
The two hoses that run thru the firewall into the heater core should both be hot. Check them with your hand; you may need to flush/replace your heater core. I hope this helps you. Mark
Do you live in an area that you need your heater?
between 6 and 8 hours
No, the entire dash has to be removed.
Check the vacuum operated valve at the hose going to the heater core.