Q1: No because other dictionaries define attendance as being present somewhere.
Q2: You're using two different tenses here (the past simple and the future simple) as well as the second conditional, which leads to three different meanings.
Q3: "Your attendance at the meeting makes me feel very happy" is perfectly acceptable. I don't see any problems here.
Q4: No problems here also.
Q5: Your attending the/this meeting makes me feel very happy.