New to G3: root, unlock, ROM specific to carrier? topic

I'm not new to rooting, bootloaders, and ROMs, but I am new to the G3. My current phone is a Nexus 4 on Cricket (AT&T), so of course everything ROM related couldn't be easier. I figure the G3 will be "harder" by virtue of it not being a Nexus device. My D850 will be here in a couple of days and I want to hit the ground running with a root and bootloader unlock. After poking around, I thought it would be easier to ask the community where to start and what steps to take.

1.) Root: I see that Stump is no longer supported; will it still work or is it because LG has patched the exploit? If the latter, is there an alternative root method you recommend?
2.) Unlocking the bootloader: I see Bump! Is this a "true" unlock (ie. I can install any AT&T ROM variant) or do I have to use specific Bump ROMs after installing TWRP? Is there any other (better) options?
3.) ROMs: I assume you can only use AT&T ROMs on an AT&T G3 variant (mine's the D850) due to the specific radios. Any known issues with using the D850 on Cricket?
4.) Any thing else I should know about ROMming for the G3? In terms of flexibility, I've been spoiled with the N4, but I'm looking forward to the hardware awesomeness that is the G3!

TIA for any and all responses! I love the XDA community :)