Custom fields and updating - activation key

Hi all,

We are waiting for This email address is being protected from spambots. You need JavaScript enabled to view it. to send us an activation key for our installation.
We made some customizing some months ago, hiding some fields in Leads and Account modules, and adding some other fields. After that we stopped the project and now we'd love to re-activate it , and maybe finish with it and go over to the full version.

The question is: after upgrading, what happens to custom fields, and customization like adding new schedules to a module?

The other question is: how much time do you need normally to send an activation key?
Thanks.
Lp.

Thanks so much.
You're great.