These terms are generally interchangeable. Sometimes, counselling refers to shorter-term, more solution-focused work, but usually these terms all mean the same thing and are a matter of personal preference. 

There is no rule for this, but for deep work to take place, a good minimum to expect is about 16 sessions.

Again, there is no hard rule for this, but it is generally helpful to attend weekly at first. This allows you to establish a relationship with your therapist and do some focused work to gain momentum and experience change. Once you are on your way, sessions can decrease in frequency. I am not firm about this — if starting biweekly works better for your budget or schedule, that’s fine with me.

There is no need to prepare for your session in any particular way — come as you are. If you are attending virtually, make sure you have a private space where you can feel safe and relaxed.