[Nook Color General] mr72:
No, most certainly this PCB has more than just two layers (which would be top and bottom). And there is no way for anything to solder a component to a pad buried between layers of a PCB.

What they were talking about is in fact a component with pads beneath the body of the component, such as a BGA or other type. And misinformed "toast" joke aside, unsoldering components with a heat gun is a pretty normal technique for an experienced solder tech, which I was doing 20 years ago. However, for a high-density board like this, without specialized heating equipment you are most certainly going to unsolder more than just the part you want to remove if you use a heat gun. If you want to strip the entire PCB, then a heat gun will work great.

To unsolder components with pads obscured by the component itself, such as BGA parts, you use an infra-red tool. Or at least, you did 10 years ago, last time I was working on hardware. Whatever the current tools are, they are well within the skill level and standard tool chest of a good rework tech. So while this may be quite simple and routine for hundreds of thousands of people, thousands in any major city worldwide, it usually is not the type of thing a hobbyist has available. So if you have to ask, then the answer doesn't likely matter.

While on the topic, however, adding a microphone or FM antenna connection is well within the range of a decent hobbyist. I would argue that connecting the FM radio antenna to the headphone jack is not even close to the best way to do it, even though it may be common for phones. This makes the FM radio unusable with a bluetooth headset, or the built-in speaker. No worry, you can still solder in an antenna and just hide it in the bezel of the NC. But if you have to ask any more than that, then you don't probably have use for the answer. If you understand FM radio antennae in the least, and you know how to solder a 30ga wire to a ultra-fine-pitch component lead, then you will figure the rest out. Getting software to use it, and especially to ignore not having a headphone connection, well that's another matter.

Adding a microphone internal to the NC is also likely easy, but the software would have to be made to support it. The audio component has pins to connect to a microphone as well as a line in. I doubt these are supported by the driver since they are not connected to anything. A sub-$1 electret element could be glued into the bezel, and you'd just have to drill a tiny hole above it and route wires to the pins on the audio chip. A little Tac-Pac here and there and it's a done deal. Now if you also want to write driver software then you might be able to use things like voice search or skype. However, adding support for external microphone over a TRRS cable like an iPhone or HTC headset would require a different headphone connector, which is integral to the bezel. That is not a reasonable mod to undertake.

Now, the dev community is unlikely to ever undertake the task of creating software support for these simple mods (FM radio antenna, mic) since the hardware does not support it at all. You might get lucky and find a driver for another device with the same components. In any case, making it work is going to be no small feat and only will work with one-off, modified devices. If you want a tablet with a mic and FM radio, you probably are better off buying one like that to begin with.