Yes the 18-55 lens has to be updated, I also run into this problem when I bought the X-T2 kit, It is not something you expect when buying a brand new camera. But after updating the lens, ois is very close to the ibis of my GX85. I absolutely recommand buying the kit, this lens is definitely worth the 300 Euro/Dollar when you buy it in the kit.
For a flat setting you can probably best use negative standard with al the other settings dialled down to the lowest value.
In the Q menu you can save up to seven different camera profiles.
I picked up a X-T2 kit just for our holiday to Kos (Greece) and started shooting there figuring out the settings on the way.
After some days I choose Astia low which worked best for me under these high contrast circumstances.
I put together some footage I shot on Kos, nothing spectacular all handhold, mainly shot with the kit lens and the 50-230 f4.5-6.7, which I bought for 180 Euro.
Greets Jan