Hello again!
Chimes spawning under enemy tower:
It is intentional, that Chimes sometimes spawn in dangerous spots - either under tower (there's only one potential spawn place there) or in the enemy jungle. This is to give the Bard player something to strive for. The chimes you collect feel all the sweeter when there's some you can't get to, and when you DO manage to get the towerdive kill and grab that #!@* chime on the way out, it feels even better.
That's part of the reason chimes are frequent, small power - I can afford to have the spawner put them someplace weird or inaccessible occasionally, since it will even out over the course of the game out of sheer numbers. I call this design technique "cheating" >_>
Pro play
I'm very interested to see what pros do with him. He's the kind of character that I put these tools on without a full idea of what the possibilities are, just that he can do crazy things. It's possible that in his current state, pros won't be able to find a use for him - I'm making some guesses at how things will play out, and if they turn out differently we can apply nerfs and buffs accordingly :)
My theory on it is that the teams will have to find a way to take pressure off their ADC (killing at level 2, shoving wave, early jungle ganks) in order to "unlock" Bard from having to stay there. From there, I think Bard scales really hard with teamwork, so I think they'll be able to figure out all sorts of strategies from there.
Previous kits
Hmmmmm... a few of the abilities I tried were super cool but not good fits for Bard, so I think I'll keep those a secret for now (they're up for grabs for other designers, too - we have a very collaborative process).
Early on, when I was just looking for an in-lane hook, I tried out Bard as "a support for assassin players." He was a close-range trickster, with a stealth that he had to channel (like Recall) to enter, a directional knockback, stuff like that. He would clear the ward from his lane brush, and then zone the enemy team. The idea was that if you ever lost sight of the guy, he was just gone. The kit had a BUNCH of gameplay problems (it was my first stab at a kit) and also ended up fitting Bard's thematic and character pretty poorly, so it got scrapped.
Good ADCs for Bard
The ones you mention are good for the reasons you mention (Cait/Corki/Ez, for safety). I've also seen a very successful Sivir/Bard lane, since she can shove the lane so hard that the enemies can't get any pressure on her. Also, strangely, Kalista/Bard has seen some success internally - you don't make much use of her W passive, but her scouts, mobility, and shoving power keep her fairly safe, and her ult can pull back Bard from a mid-length roam very quickly.
Edit: Aaaaaalso, I'm really curious if it will turn out that Bard+is a good lane. Bard/Velkoz or Bard/Cass might be a thing... gotta get that sweet sweet solo lane XP, after all.
Thanks! You ask interesting questions, so I'm happy to answer them.
(Also, you were lucky enough to post right after he released on PBE - I got buried in bugfixes soon after, so to anybody who felt neglected on the PBE forums: I'm sorry! D: )