Mounting 13 cm speakers in the back is quite simple: you cut that material under the rear window with a solid cutter (you have to stay in the trunk to do that) and then you secure the speakers with screws.

The cabling looks more complicated at a first glance. Although I do not have a cable that is so expensive to get all the attention when installing it I thought it would be a good idea to keep it as far as I can from the power cables so I chose to run it along the central tunnel.

Bill of materials:
- 2 pieces of audio cable 4 meters in length
- 2 meters of "single-core", rigid wire
- 1 ISO connector (easy to find in audio stores) or the metal connector that fits an ISO connectro (I could not find such items)

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1. Take out the back seat. Unscrew the plastic covers between the front seats and the gear stick.
2. Run the rigid wire underneath the carpet (you insert it through the open space where the parking brake's cables are visible) and stick it out near the center column (use the spaces near the gear stick to guide the wire)

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3. Tie the audio cable to the rigid wire and stick it out the space behind the parking brake. Use the rigid wire to pull the audio cable to the remaining length of carpet that is the one in front of the back seat.

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4. Guide the cable towards the edges and run it into the trunk.
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5. In the trunk the cable is inserted under the side carpet (which is not attached at the bottom, it's only a "carpet cap" on it) and connect it to the speakers.

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6. Remove the existing head-unit from its place. One handy man will stick the cables we've just installed through the gap left by the head-unit.

7. Next we'll need the connectors that run in the rear of the head-unit. I obtained them pretty hard by cutting an ISO connector (the one in the picture of the needed parts)

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8. Connect the metal ends to your cable

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9. Insert the ends into the connectors in the empty slots (you can see that in the picture); UP is for + and DOWN is for - (LEFT as we look from the seat is the left speaker and right is the right speaker)

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10. Put the head-unit back in place and that's it.

1st answer: no
2nd answer: I do not know, but AFAIK there is something about this in the Romanian section. If I have the time I'll look for it and translate that for all you english speakers out there.