There are actually several versions of Gandalf in the set (including Gandalf the White, whose color identity will not surprise you), and we show him at different points throughout the story by making him different colors
For the appropriate size we recommend scaling between 100-105%
Probably a bit slow for some older formats, it was just played in way too many decks in Standard
As far as the flavor of the card goes it's not exactly clear what the abilities have to do with this character
Oko is just value by itself
Without these cards, it's likely White Weenie will return to the "play a bunch of one-drops and pray for no sweeper" play style, which is admittedly a play style that can steal a reasonable number of wins, especially for a budget-friendly deck, but is unlikely to keep the deck as a truly competitive, top-tier option in post-rotation Standard