Too bad your radio got some damage. Maybe re-bend the fan housing or just take it off if it won't collect too much dust.
The tuner could be bad or possibly your antenna is too far out of range for it tune. Most built in tuners on HF rigs won't tune an antenna higher than a 3.1 SWR.
As for mics, you just need to get the mic wiring for your Xtreme 2018 and compare it to the your Kenwood. Be sure to look at the Kenwood diagram carefully to determine what side is pins 1-4 and pins 8-5. Most likely you only need to wire pins 1, 2, and 7.
Here is the 8 pin Kenwood wiring for your radio and other Kenwood models
KENWOOD-TS-50-60-140-430-440-450-570-660-670-780-930-430-670-711 TS-811-850-870-930-940-950-440-701-790-680-690-TS-2000
TR-3200-7900-7950-50-751-851
TM-201A-201B-401A-TM401B-211-221-231-241-321-331-3530-421-431-441-521-531-541
TM-621-631-701-721-731-2530-2550-2570
TW4000-4100
PIN1 MIC
PIN2 PTT
PIN3 DOWN
PIN4 UP
PIN5 + 8VOLT Some models ( 10 Ma )
PIN6 (N/C Some models )
PIN7 MIC GROUND.
PIN8 GROUND ( STBY )