First of all, interest in this project never annoys me As for new connector, of course, it will be "bonus feature", i.e. it won't replace standard antennas. It's going to be additional possibility, but you won't be forced to have external antenna connected every time You want to use any radio capabilities.

Precisely speaking, it will be one, standard antenna mini-connector - with three cables on the "inside" of body, that are to being connected into hirose U.FL ports on board. This way, depending on external antenna connected, You will have either Wifi and bluetooth (both are 2.4 GHz, so same antenna works well), GPS, or Cellular signal boosted. Generally, ranges wary so much, that different external antenna will be required for those three applications, but is it possible to DIY construct special, fractal antenna, with max resonance tuned for those 3 frequencies at once. Which is my plan to do after finishing this project

No worries, I won't allow FM transmitter (or any other) signal to be reduced. All internal antennas are going to work fine. It's yet to be decided, if I'm going to re-use existing ones (they're easily removable from case, during disassembling), put into special "sockets" in new body (by every user, during moving N900 to new body), or if I'll be forced to re-create internal antennas, but for sure having them working fine is a must.

Furthermore, I'll try to come with a way to allow external antenna connection for FMTX too, despite limitations - hoever, here I can't promise anything, yet.

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BTW, as for FMTX power, have You tried using jacekowski's modified fmtx binary, together with kernel-power? It should allow You to have transmitting set to max permanently (even when device is connected to charger). In my case, it allow for absolutely clean transmitting across few rooms (walls), or to car following me on road (with some distortions at the latter).

/Estel