1.) Stay at the Wing, not the Pier, waiting for the 5xx gates. It's about a 3-5 minute walk down from the Wing. Noe that all 5xx gates require a bus; so that's the time to get down from the lounge to the bus departure (which is where your boarding card is processed). If you insist on staying at the Pier, I'd allocate about a 10-15 minute walk depending on your walking/looking at aircraft along the way speed. Note you cannot take the train back from the Pier (which is near Gate 62), so if you insist on coming back to the 5xx gates (which are really underneath gates 15 and 21) you will need to walk it.

2.) The 5xx gates all require busses, departing from a similar area. 501-511 are proper gates in a terminal-type facility, but unfortunately it is an island in the middle of the apron and requires bussing. The others are traditional stairway-to-the-aircraft boarding accessible by bus. You've got a higher chance of the 5xx gates on the morning departure with KA's A321 to PVG (and note that plane won't have F on it) than you will with the A330 (which probably will have F, but there's always the outside chance KA swaps on you to one of their two-class configs).