1. It is only in several states at once if it is not observed. In fact, if a particle is not observed (not interacting with other quantum systems) it has a probability of being in any position. There is something called the wave function, represented by [latex]\psi (x)[/latex]. The wave function is a function such that [latex]\int_a^b \psi (x) \psi^* (x) dx [/latex] is the probability of observing the particle between position a and b, where [latex]\psi^* (x)[/latex] is the complex conjugate of [latex]\psi (x)[/latex]. When a particle is observed, the wave function collapses and you observe the particle as being in a certain position. The wave function is basically a function describing the quantum system and how it behaves. The wave function can be a function of space, time, or both. There is also a momentum wave function represented by [latex]\phi (p, t)[/latex]. The two wave functions are related by [latex]\psi(x, t) = 1/h^{1/2} \int_{-\infty}^\infty e^{2\pi ipx/h} \phi (p, t) dp[/latex] and [latex]\phi (p, t) = 1/h^{1/2} \int_{-\infty}^\infty e^{-2\pi ipx/h} \psi (x, t) dx[/latex], where h is plank's constant.
2. We don't know