Yes, I have (and still do) invested in in performing and non-performing notes, firsts and seconds.
Your questions are way too broad to answer in a single forum post. I've been to whole weekend conferences on notes that barely scratch the surface.
Your post is like saying "I want to buy a house. How do I evaluate a house, and how do I landlord, any tips for that?"
The bottom line on all properties or notes: Due diligence. If there is enough equity, pretty much everything else doesn't matter. If you can get creative, equity doesn't matter either. The property underlies the note, so make sure it's a property you're okay owning (for at least some point) if that ends up having to be a last resort exit strategy.
If you have more specific questions about a particular note deal, servicing, etc. I'd be happy to share what I know. Your post though leaves me with not knowing where to start (especially since I don't know your level of expertise already).
