4.7 to 5.0 when using CCK

I have a 4.7 site where I used to CCK to create some content types with a few fields that 4.7 did not support. I now want to upgrade that site to 5.0.

Assuming that the fields I created are supported by the various CCK add-ons for 5.0, what kind of trouble might I have upgrading the site?

Will the custom content types I created in 4.7 automatically port to 5.0?

What will happen when I try to display a node using one of those custom content types if there's a field in the node that 5.0 does not support?

Thank you!

Bob...