For us, we start almost 100% of the IV's for surgery. We do it in our holding area. Many moons ago, the anes. people (doc and crna's) didn't want us to touch "their IV'S"

BUT, over the years that has changed.
We also were taught to numb the sites with bacteriostatic NS, which helps in many cases.
The anes docs still do the hard ones, that we can't get. But I tell you, several of the nurses are very good at it.
As far as size of IV, I guess 18 is the standard, but we try larger if the case looks to be a bad on, 20 or 22 if a small child.
One anes. doc. says to get in what we can...he would rather have a good 20 in the arm, than a 18 or 16 in the trash can!!