Awesome stuff, I'm glad it helped.
I'm a veggie, so I can be a bit more up to date with my references, love the attitude of good food btw. BBQ is pretty meat focused thing and veg/veg isn't cool :D
Biggest thing, don't cross contaminate, esp when cooking for vegans. Us veggies obviously eat things like cheese and for me personally I wouldn't be bothered about same tools surface etc, but someone who is avoiding all animal products this needs to be cared for. That being said, most of the vegans I know also wouldn't really care if accidents happen, so don't fret it too much.
My Brother in law cooks all the veggie stuff first then meat, but you could also do separate cook surfaces he has a little green egg and a big one, so our stuff goes on the little guy as veggie stuff doesn't require a lot of cook time.
Remember the fat thing, there's a weird psychology that veggie/vegan has to be healthy this is nonsense as cookies exist. Coconut oil is a great fat for BBQ as it's got a really high flashpoint, and you can use it a bit more like bacon grease unless you live in a hot place.
Vegan ALT meats are really good now be sure to either buy more or hide some for the people that need them as non veggie and vegans will eat most of them as a curiosity and leave no options for them. Super awesome people want to try new things and I wouldn't care in a social gathering, but sometimes it's your main meal of the day that you save for. This happened at my Mums wedding they just put all the veggie sausages and burgers out together and there wasn't much to start with so we had dry bread rolls with coleslaw wooo :)
There are so many cool recipes out there, maybe find a veg/veg guinea pig to test on before a big event what wouldn't pass for a meat eater could be amazing for a veggie.
Halloumi is peak for everyone no wait not vegans,
Marinades plants are all about transporting stuff about stick em in something nice for day before even watermelon?
If you want to really wow people check out SauceStache he likes to do all sorts of weird and wonderful things and even just one of these will have people requesting them :D