I'm currently bronze and I'll be doing quite a few flights/around the US this summer and was thinking I may make silver or even gold. However....

(1) The BAEC website states that the tier thresholds are 300, 600 and 1500. But are my points re-set once I reach a threshold i.e. does this mean I must make 900 to make silver? Or it is simply 300 more than the 300 required to make bronze?

(2) I will be making return internal flight from NYC to PDX and I'm looking at doing a YUP on AA via DFW. Would this route get me tier points for EWR-DFW and DFW-PDX? And if so what would a YUP to F (but booking into P) actually get me? The tier points calculator on BA won't let me calculate this.

(3) If my status should change during a trip (i.e. on the outbound I should silver but inbound I should be gold) would this be applied to the mile calculation or am I silver for the whole trip?

If anyone is interested my routes this summer are:
AMS-LHR-IAD (RTN) in CE/CW
LHR-JFK in F
JFK-LCY in CW
LHR-JFK in CW (MFU from WT+)
EWR-DFW-PDX (RTN) in F (YUP) on AA
JFK-LHR in CW (MFU from WT+)

Thanks FTers