If you want, you can soak the corn before putting on the grill but it is not necessary. There are enough layers of shuck to protect the corn. I have done corn on my weber many times and have done it both ways. If you have some sort of cover, they would help steam the corn, but again, not a deal killer if you don't.
The smokers would work just don't add wood and get the temp up to about 300 or better.
Roast corn is big in south Texas and they use big propane rotisserie trailers.
Make sure to have some good gloves to shuck the corn. Once roasted, the shuck and silk come off pretty easily but they will be HOT!
Condiments for South Texas are: Butter, Salt & Pepper, Chili Powder, Parmesan Cheese and Mayo. Personally, cannot stand the thought of Mayo on corn but my daughter loves it.