A question about replacements in an ACW Campaign Game

[Steel God]

Okay, so I've read through the Users Manual and can't find a reference, and I want to say it was discussed in the forum too, but having scrolled back several years in posts in this forum and not finding anything I'll just post it up.

When you are playing the Campaign Game (PBEM but that shouldn't matter) and a unit takes losses are they permanent or does the unit come back whole next battle?  I have the notion in my head that I read somewhere that a unit will recover 10% strength between battles (e.g. a regiment of 400 that takes 20% losses would be at 320 at battles end and in next battle would be at 320 + 32 = 352).  But I can't find where I would have gotten this idea from.

Likewise, what happens to destroyed units.  If a regiment or battery is destroyed completely, via fire or melee, is it gone for good?  Or does it come back as some sort of cadre strength?

Finally, are there an impacts to the quality rating of a unit when it comes back? 

If units come back whole like zombies between battles there would be very little point in playing a campaign game, so I hope someone can point me to documentation that will put my fears to rest.