1.- As an individual, the cheapest and simplest options would be to use Nanoracks, Spaceflight, or a similar company that handles most of the launch process. Their price is ~$100k for a 1U Cubesat. I have serious doubts that they would be OK with a 3x3x3 cm satellite, as these are really hard to track and they are big enough that, if there is a collision, they can cause some serious damage. See for example https://spacenews.com/fcc-fines-swarm-900000-for-unauthorize...

2.- Yes, there are. For example, in terms of materials, you can check http://nanoracks.com/wp-content/uploads/standard-materials-a.... Yes, in satellites there are several things that normally unfold (i.e., solar panels, antennas, sensors)

3.- They normally undergo (at least) outgassing, vacuum, vibration, and thermal testing. Not sure if all of them are mandatory. I would say that outgassing is a must in most places. See http://nanoracks.com/wp-content/uploads/flammability-offgass...

4.- Yes, some people have launched things much much smaller than a Cubesat (like Chipsat), but normally you would be required to decay/deorbit quite quickly since as I mentioned, space people don't like small things flying around.

5.- If you use a launch provider, you normally do integration at their facilities. Then they handle the rest of the process for you. I would say that a normal deadline for integration is ~3 months before launch?