Solution to 1: Night Tour Views
The title of this puzzles makes a reference to the "Knight's Tour" chess problem, where the knight chess piece visits every square on the board exactly once. The word "before" is italicized, hinting that the starting point is B4. However, there are only two possible start/end points once the path is found, so solvers could have tried both even without catching the clue about B4.
Finding the path and taking the corresponding letters from the grid of letters below gives the sequence of letters "OLHRCCBAKCBAVO"
Now, you should use the sequence of numbers in your friend's email to index the letters. The index 728694159 corresponds to "BLACKROCK", which is the answer.
Easter Egg: The email address whodis728694159@gmail.com actually exists and was owned by the Questmasters. If you had emailed it, you would have gotten a super secret hint.
Just kidding, we just replied with random stuff.
BLACKROCK