1. There is no dedicated forum, but using the search feature you can find cooks and modifications others have made.
2. The charcoal grate is designed to float because tabs would just fail under the weight and molding the bowl the way the top grate sits would be a pain. You just need to be careful inserting the grate and use fire bricks to balance the weight.
3. People will put coals all over for big direct cooks or pile them to one side where the grates flip up. People have made their own baskets and rims attached to the charcoal grate but they are custom made. Others have dropped a pretty penny on the slow n sear xl for both sides.
4. I wouldn't bother with dome thermometers. The bowl is so huge the temp will be different from one side to the other. You would need probably 4 of them to keep an accurate reading. Look at a thermoworks wireless thermometer and it doubles to keep temp of your meat.
5. People will use the basic foil pans and others have fabricated custom drip pans that fit with there charcoal baskets.
6. You need to buy some good welders or grill gloves to handle the grate. When lifting I think flipping up the sides and grabing the middle works best. For spinning the grate they do make grate lifter tools that make it easier to spin. You will need 2 of them though.
I am not an expert on cooking on it. Just bought one and getting it back to like new shape. However I have been searching all over for advice, mods, and etc. Good luck!