Any time people mention the "what if" questions I just say "we'll cross that bridge when we get there!" As far as not using an agent, that's up to you. I'm biased since I'm an agent here in Las Vegas but it is possible to buy or sell without one, there's just tons of documents that need to be signed. As far as the step by step checklist, I haven't seen one so this might be the perfect time for you to document every step that you take and then you'll have it for later!!!
The best way to deal with bad tenants is to avoid having them. If you have a great list in place for you to pre-screen them before you ever take any of their money or let them in then you shouldn't have as hard of a time, however, lots of people lie so you must check and double check after people. Actually call their references and ask them probing questions. Actually call their previous place of living and ask if they'd rent to them again. Call their boss and ask about them. Those sorts of things.
I'm sure I'm missing stuff but others will chime in I'm sure.