Hi and welcome to both of you! Be sure to stop by the rules thread and post your acknowledgement there. Let's get to the answers:
1. No. the Dominix/Aeon design does not have a removable emitter so it cannot be interchanged.
2. When you purchase a saber with sound you can have the blue AV switch installed.
http://www.ultrasabers.com/product-p/sound-dominixv3le.htm3. You need to know about electronics a little and how to use resistors to adjust voltage to the LED and how to solder. The wiring is fairly simple but you need to have an understanding of the way it all works. For that, you can go to the technical thread and look around for the topics you want to learn. Buying a saber with sound is a cheaper way to do it as getting all the individual parts yourself is more expensive. It would be a fun project nonetheless and many members here have done it. The time it would take depends on your skill level. It may take only an hour or two if you really know what you're doing, but it might take several more if you don't and if you damage or break the soundboard then you have to order a new one.
4. The blades are secured or removed by way of a tension screw that you can easily adjust with a hex wrench (included for an additional $1 on the saber options page) otherwise that one would be a 5/64 hex if you have those already. I like the ones they have cuz I just stick one in my pocket when I go places.
5. The heavy grade blades are made from a clear polycarbonate with a reflective film inside that lets the color show evenly along the blade. If you are worried about durability, the midgrades are very strong still and the balance is a little closer to what lightsabers would feel like as the balance point is much closer to the emitter that way. They hold up just fine to dueling too. If you really prefer a front heavy feel then heavygrade is fine too.
Good luck, and enjoy! feel free to ask any questions you have, and you may find the answers already given in the Questions section.
