If the paper is cold pressed, should I assume that 300 GSM paper will have more teeth than 200 GSM paper?
Does higher GSM mean more teeth for cold pressed paper?
The GSM level does not necessarily dictate the tooth of paper. GSM stands for Grams per Square Metre and refers to the quality of the paper in terms of thickness. A 1m x 1m sheet of paper at 300 GSM will weigh 300 grams as opposed to 200 grams with 200 GSM.
The tooth is down to the compression method used to produce the paper. Cold Press paper is rougher than Hot Press and you would need to try different brands to find your desired tooth.
If you have paper which has a higher tooth than desired you can follow the advice given in the second link.
Using the finest sandpaper at your local art store, gently sand the paper until it arrives at your desired smoothness. Be careful to pause in between vigorous sanding sessions, and check that you are not sanding a hole into your paper.
As you probably guessed, for the opposite (to get more tooth), use sandpaper which is more coarse. Be very careful with this thought as the tooth in patches can become uneven and you won't need to rub much for this.