Dick Grayson, Barbara Gordon, Alfred Pennyworth, Tim Drake, Cassandra Cain, Stephanie Brown, Damian Wayne, James Gordon, Jason Todd (maybe), the Justice League, and Kevin Conroy.
He would know all the same people he knew before he got married.
The Joker would not invited.
Probably Batman
Nothing. You would get the capacity to send even more invitations. You can never run out of Invitations.
If Batman got married, it's likely that the Joker would not receive an invitation. Their tumultuous and adversarial relationship makes it clear that Batman would want to avoid any chaos or disruption on his special day. Additionally, inviting someone like the Joker could lead to unexpected and dangerous situations, which Batman would surely want to avoid.
His butler, Alfred Pennyworth, would be invited.
Most people would not get an invention. Inventions are few and far between even among fictional super heroes.
I would go to the party center which they really sell a lot of great invitations and gift cards. I would also look at invitations.com which would really help people make things easier.
He is a fictional character and this is not possible.
It would be acceptable to send out invitations by email for a seminar. Many people use templates from email sites such as e-vites. In addition to being able to track the delivery of the invitations, you also have a quicker response time.
you and any norrmal citizon also anyone he is an enemy of
There are many internet sites where engagement party invitations can be found to buy or to print. Vistaprint.com would be a good site to use if you are planning on printing invitations.