Hello

1 In practice it's usually best to mine to closest startum server. Geography doesn't always mean lowest ping so a good rule of thumb would be to run a ping test on the servers to find your best match.  

2 mining pools use share difficulty to throttle the speed at which you get work from the pool.  18 shares per minute seems to be close to what most pools use.  they do this in order to not flood the pool with requests for data. For instance if you rent from nicehash and point to coinmine with 10000sols/s then you find about 50 diff 192 shares per second at normal luck if you point to port 7007. If you point that same hash to port 8088 which says static at 500 but is really 32000. Then you would find about 1 share every three seconds with 10ksol/s. Hope that's not too confusing

3. I would point them at 7007 being as they are so close to starting diff.

BR
d57heinz