Q1 > We will have access to the civilian level service, as we do GPS / GLONASS. We won't have control of that system, or the military grade high-resolution service.
Q2 > The overall project is being run by the ESA, but is being funded and managed by the EU. The security aspect of the whole project is controlled by the EU.
Q3 > Other third party states are involved in the project, but they don't have access to the secure aspects of the system and are not eligible to bid for work on those aspects. Once we are a third state, we will be able to bid for work on the same terms.
All of these issues are the exact same as we face with GPS - we can use the public system and we can bid for work that the US don't consider to be a security risk. The secure stuff, nope, that's for them to keep to themselves. If it wasn't for the whole Brexit malarkey, nobody would even bat an eyelid at these restrictions as the same thing happens all the time, all over the world. Chuck Brexit in to the mix and suddenly we have to blame someone for being unfair.