The liner suggestion was if you were going to bake bread or pastry straight away in your new DO, savory dishes = no liner.
The seasoning is basically built up layers of carbonized fat (animal or plant) that makes a natural non-stick surface. On an old and well used piece of cast iron you can cook anything and it will have little effect on the seasoning, but in my experience younger/newer cast iron seasoning does not stand up so well to highly acidic recipes. So I would avoid dishes with a lot of tomatoes or other tangy fruits, at least initially.
I think it's also very important to clean and oil your cast iron ASAP after cooking. My wife was fond of frying something up in my stove top DO and waiting until the next morning (or the one after that...) to clean it up. I found out the hard way that a coat of cooking residue (even pork fat!) will loosen up and remove your nice seasoning if you leave it sit too long...

Now she's not allowed to use MY cast iron unsupervised!!
I think you ought to break in your new camp DO with some savoury roasted dishes. Stuff that's going to put animal or plant fat in contact with your cast iron in a dryer environment. Wait until you get a bit of a layer built up before braising or stewing as the young seasoning doesn't seem to like a lot of moisture, either.
I'm sure there are a bunch of folks here with way more cast iron cooking experience than me, but these are some to the things I've noticed over the years...
Regards-HW