What gives me Anxiety Half an Hour Before Getting On the Bus To Paris

I'm coming back this evening and being alone in Paris is really not that big of a deal, I'm actually looking forward to it, but...
  1. How again does the bus payment work here? Do I just get on the bus and ask the driver for a ticket like I would in Germany?
  2. What if I don't have enough time at the train station to get my pass Navigo and am going to miss my train?
  3. I forgot my city maps at home and won't be able to look ansthing up on my phone. I'm pretty sure that I won't get lost, but what if?
  4. I do not have a real idea about what I want to do today. Where am I going?
  5. And last but not least: Will I coincidently meet @Lisa_Fav on the street and recognize her (or not recognize her)?
    (Yes, I know that this will most likely not happen but what IF?) Will she be mad because I spent a whole day in Paris without telling her?
  6. Oh and now I have a new problem: Am I still able to be on time for my bus after writing this list????
  7. I REALLY need to go now!