Booked three trips back to back for October 6, 7, 8

We need to call Delta to enter our NW number so the miles are credited to Worldperks, right?

For NW operated flights I assume the upgrades will be EUA? How do we choose seats on them anyway, by calling NW or DL? ( I doubt we can do that on nwa.com)

Based on the last MR seminar I attended, I swore to do "Book now, think about it later"