First, im going to tell you it is HIGHLY recomended that since you are going to be working in the round, you should do your swatch in the round as well...(smaller scale of course). Gauge can be sneeky and change when you knit in the round, from what you knitted flat...
Next Ill tell you to do your swatch in stockenette(Flat: knit one row, purl one row, In the round: Knit all rows)
All your pattern stitches, ribbing, ect....fall under that swatches gauge.
This is how its done for all patterns, unless the pattern tells you otherwise....(theres always a "unless" isnt there?) If it says nothing about it, and just tells you gauge, do it in stockenette.