You aren't the only one who only wanted one and not twins CT!! I admit that we had two put back to give a better chance, not for wanting twins but I wouldn't swap them now, they're great.
The potential difference between ICSI/ IVF babies (singleton/multiple whatever) is that if ICSI is used, the selection of sperm to egg is determined by the embryologist rather than leaving it to nature.
Conventional IVF is more like nature in that the sperm and eggs are left to their own devices therefore the strongest sperm gets itself the 'prize' egg.
My parents have a friend who is an identical. She and her sister are so different it's amazing that they are identical. Our two have a much stronger bond with each other and they cannot possibly be identical since they are boy/girl.
There is nothing else that would make an IVF pregnancy / birth / upbringing any different to naturally conceived.