from xianlin avenue, Qixia District, Nanjing to IKEA 99 MingShi Road - do I get the metro line 2 into Zhonghua gate station?

Yes, you are right. The IKEA is about 5.5km.
From where you are, you need to take the metro line 2 to Xinjiekou Station and then change to line 1 to Zhonghuamen Station. Then take a taxi to the IKEA.
Or you can only take the line 2 to Xianmen Station and then take a taxi to IKEA. From Xianmen to IKEA, there is about 6km.

Great thank you, both options look good.

One more request, from th Xianlan NJ University campus (near the end of Line 2 metro) what is the most efficient way to the international airport. (I have little luggage). Thank you, I appreciate your help.
Jodi

You can take the local metro line 2 to get to Xinjiekou Station and then change to line 1 to South Railway Station.
From the South Railway Station Bus Station, you can find the airport shuttle bus line 1 to reach the airport directly.
Hope the information can help you.

Thanks Tommy - wish me luck. I tried the bus/metro tools but it would not recogonise xuexilu metro station / tried the spelling on the metro matp too, but with no luck. '
I appreciate your help.