Great don't come! Feel free to say you are honored to be invited but you just don't feel like it, or even eh I didn't think we were that close but I have to come? This day isn't for you so don't feel bad about not coming. You can always leave a little thank you in the registry if you want.
Not really, if you must bring them then that is ok. This will be an adult-focused event and there will be candy and espresso available for the children at their convenience.
Your invite may say 1+ but due to COVID issues and restrictions, we may only have invited you. We will make sure not to invite anyone who doesn't know others that will be in attendance.
Clothing is not optional.
There are a bunch of places you can rent in Oshawa and Whitby. Our house will only hold about 6 people and a cat.