What should come in place of the question mark (?) in the given series based on the English alphabetical order? UXX, VSU, WNR, ?, YDL

Complete the following series: 7, 15, 29, 59, 117, ______

Which letter should come in place of the question mark (?) to complete the series? B, D, G, K, P, ?

Which number should come in place of the question mark (?) to make the series logically complete? 527 524 529 522 531 ?