Rudi,

1. Its acceptable, I'm just not sure if its wise (esp. in a public place like a bar)
2. Why leave any question: Just take 10% of the bill. Add Half of that to get a 15% tip, double to leave a 20% one.
3. The owner will definitely pass the tips along. Leaving cash would probably make it easier to cheat, but it doesn't really matter since the IRS will usually just estimate tip income and tax accordingly.
4. Not sure about the 2-tip column. I just write what I think is an acceptable total and circle it.
5. Handling your own luggage is acceptable, I think.