Gre reschedule

HiI am trying to reschedule gre test, but here they are asking me to pay 115 dollars, While registering for gre i appl

Admits from UChicago MScA, NEU MS- DAE and CU Boulder MSDS

Which one should I go for? UChicago course is the shortest which is my only concern(15 month)

Do Professional LOR’s require any stamp from the company?

Do we need to get the lor sealed / stamped or is it not required and can we submit a pdf?

How did you write SOP in a great format & with excellent vocabulary?

Please give any resources you relied on. There are many websites explaining format in brief but how did you guys write 2