Well I have been in nuclear power for about 10 years now. But much of that time was as a plant operator, so not much design. I changed jobs and I've been in I&C design for a couple of years now. There are definitely folks out there with more experience than I have, so I'd keep asking around to...
I am an I&C engineer working at a firm doing nuclear plant design. The job is very fun! I don't have a mechanical background so others will have to speak to that particular transition. I'll take a stab at your other questions though.
1) Assuming you're in the US, NRC regulations are going to be...