No, but you can use an alternate method to configure Quartz. If you type "/quartzdd" you'll get a dropdown menu configuration instead of the default window-style configuration, and if you type "/quartzcl" you'll get command-line configuration. Either of those should let you access all of your textures.
You don't need bar identification. Look at the code in Quartz's GCD module and look how it watches for the cooldown event firing on a specific spell (such as Find Herbs). There is no way to detect the GCD directly; you just have to find a spell that cannot have any cooldown other than the GCD. I no longer use Quartz, so I don't have the code available to look at myself, and don't have time to do the research and write the code for you, so pointing out in the direction of code that works is really all the help I can provide. Use the API reference on wowwiki.com to help you work out what does what.
Likely you'll find it easier (as well as more educational) to track the GCD yourself; just pick a spell that can't have a cooldown other than the GCD, such as a tracking spell, and watch for its cooldown. That's what Quartz does, anyway.
Those of you who prefer a longer loading screen can simply use the override function in AddonLoader and set everything to "Always", and that's a lot easier than re-adding AddonLoader support after every update. :p
Not at all. Delayed loading will always cause a noticeable split second freeze.
X-LoadOn-Delayed would be fine. I expect a few seconds of stuttering pauses on login once the loading screen is gone anyway, while the game loads all of the models, textures, shadows, etc for everyone else in Dalaran. I just hate staring at the loading screen for 45 seconds.
How about something that at least hints at the addon's purpose? I've always hated names like "Quartz" that give you no idea what the addon might do without reading a description. The above suggestions like "SwissTiming", "Rolex", and "Cesium" are just as bad -- they convey images of clocks and watches, not a WoW casting bar addon.