Our first time flying Emerites. Economy tickets for two senior-ish citizens.

We have a preference to sit as far forward as possible, but not in the rows that tend to have small children. DH likes window seats, forcing me to sit in the middle.
1. How many flight attendants are usually on this plane and what is the approximate number in each of the three classes of service?
2. BOS-DBX Boeing 777-300ER. We have seats 19K and 19J. Comments?
3. After 3.5 days in Dubai, we are on to Cape Town, Emerites also Boeing 777-300ER. We have seats 28A and 28B. Comments?
4. Return flights are the same type planes. CPT-DBX seats 28K, 28J. DBX-BOS seats 20A, 20B. Comments?