Electronic – Arduino Cellular Shield EMC Testing for FCC

I have designed an Arduino shield that uses an FCC pre-certified and PTCRB cellular module and I'm wondering about EMC testing and FCC compliance. However, the main concern here is that I am using a different antenna and I read that I have to use the same antenna(e) that the module used during the certification process in order to not have to completely re-certify it for FCC ($10k+ and FCC ID and all that jazz). The weird thing is that Adafruit doesn't certify any of their FONA cellular boards even though they use different antennae from the ones in the module's certification. And how could you possibly get the exact same antenna that was used in the testing anyway? There are so many antenna knock-offs that may or may not even work. Check out this post in which Adafruit explains why they don't have to test their boards. In response to a question why they don't certify their boards Adafruit replies that "Because of our FONA boards, we're officially listed as a cellphone manufacturer" which basically sounds like "because we sell cellular modules we are officially listed as a cellphone manufacturer and therefore we don't have to certify our products" and that simply doesn't make sense to me.

To summarize, my questions are these:

1. Is it legal to sell these shields without doing EMC testing or by only doing radiated emissions testing, or do I have to get it completely FCC certified with the new antenna?

2. What about selling the shield to users in other countries? For example, Adafruit sells both an American (SIM5320A) and European (SIM5320A) version of their 3G module. Specifically I'm asking about the case in which the EU module (like SIM5320E) is CE certified. I understand there are specific laws for each country within an overarching region but I also read that you have to pay each country a registration fee? So if you're selling the board all over the world, how on earth would you afford every single country's fee? I notice that Adafruit doesn't mention where to use their product. By not explicitly mentioning specific countries or regions are they getting away with testing?

3. Can Arduino shields be considered as "subassemblies" like what Sparkfun does to avoid testing? I would be selling the shield as a standalone module and it could be wired externally and not in the sense of a "shield". In fact, as-is it can't even operate on its own without a host, even if you powered it up by itself. I just don't see how doing EMC testing on a complete assembly (host board + shield) could make sense if I don't have control over what host board the user is going to choose. However, the caveat here is that the legal verbage seems to indicate that you can't say it's for Arduino specifically, otherwise it can't be considered a subassembly: "Subassemblies to digital devices are not subject to the technical standards in this part unless they are marketed as part of a system in which case the resulting system must comply with the applicable regulations." So if you say "shield for Arduino" or "works with Arduino Uno, Mega, Leonardo" it's no longer a subassembly? That sounds like rubbish to me and shatters all common sense of the term!

There's so much stuff involved with the certification process, it's driving me insane! Thanks to anyone who can clarify!