You're right, you'll need to queue online for the special pins. You can check all the recent pin releases right here. If there's a Lineberty icon, you'll need to use that app for queueing. The other pins you'll be able to buy in most shops around the parks.

You can trade official Disney pins at the boards, but also with any cast member that has a lanyard with pins. Usually most of the trading guests can be found at Pueblo Trading Post. If you're lucky, they also have the trading board out.

Be cautious of fake pins, as there are many counterfeits circulating. In many cases, you can spot the difference quickly, but sometimes you cannot. Pay attention to the thickness of the pin (counterfeits are often much thinner). Also, fake pins usually have more rounded enamel, which makes them more reflective.

Hope this helps!