You're going to be spoiled now since Whirlwind is your first game. An absolute classic, and one of the best, if not the best System 11 game!
That locking ball issue seems to be pretty common. There's a club group that has a good ongoing discussion about the game, you can find that here:
https://pinside.com/pinball/forum/topic/whirlwind-club-members-only
Here are a few threads helping others troubleshoot a similar problem that you're having:
https://pinside.com/pinball/forum/topic/whirlwind-multi-ball-sometimes-starts-before-the-third-ball-is-plunged
https://pinside.com/pinball/forum/topic/whirlwind-ball-lock-issue
As for the display with the segments out, that's usually just the nature of those gas plasma displays as they age. Like neon, they'll sorta fizzle in and out. I'm a firm believer in "if it ain't broke, don't fix it" so until the display becomes debilitating to gameplay, I say leave it in. As it warms up, those dead segments will come back to life.
But what is debilitating are those LEDs, holy cow. Rip those out ASAP. I mean, if you like them, keep them, but regular incandescents are going to be much easier on the eyes and really light up the artwork as the artist intended.
Most importantly, HAVE FUN! Lots of great people around here to offer their sage advice.