iPhone noob needs help on ICS - how do I unhide contacts?

Just playing around with my new Galaxy Nexus and I made a few "organizational mistakes." (You'll have to forgive me, I'm coming off 4 years of the iPhone...)

So, does anyone know how to unhide contacts? I had a few apps create duplicates of contacts (Google+, WhatsApp) and I hid those contacts (I hate messy address books!!!) because I didn't realize that I could merge multiple contacts. Now that I know how to merge, I'm unable to find the contacts that I originally hid. Any help here?

On a side note, it seems that ICS is making "connections" between contacts in my address book and outside apps, but it's only doing so in some instances. In other instances I get the duplicate contact issue I described above... Am I doing something wrong, or is this just the name of the game... (Address book management has always been messy for me on most platforms.)

Thanks!