The answer is in the forum somewhere if you search through it. But to give you the short answer, pools calculate your hashing power based off of how many shares you send. So it is a calculation of your hashing power. If you are getting fluctuations above and lower than your actual miner it is normal. So no worries
most pools have average rate for 24hrs or more days. Look for that one.
Ignore current hashrate, since it can go up and down all the time as Blue mentioned.
Mining is not always 100% the same rate at a specific point in time.
Plujs my experience shows miners apps rates are usually more than actually is.
I do not know, but their difficulty settings are brutal for me wait for one value share 20-30 min on GTX 1060 is strange.
but on the other side you aare saving network connection