I currently see a therapist who specializes in trauma and whose go-to technique is EMDR. I've been seeing her for about a year and have done EMDR off and on. I'll share more about my experience in relation to your question of how it works and shoot to answer your others. It's good you're working with someone currently and EMDR may be a good supplement to that or may not do much for you. As I wrote your questions, they seemed to reflect that you're thinking of jumping right in to EMDR with a different therapist and the effectiveness of doing that probably, in part, depends on how well both therapists and you could work to create safe spaces and how you three could co-operate in your individual therapeutic relationships regardless of techniques. Generally, EMDR makes me feel tired, but I will say that the only time I've felt euphoric after EMDR were times I felt seen and safe with my therapist. I think her being able to create a space where I can contain is what's helped EMDR be effective for me (a lot of my trauma is from a DV relationship and from some really poor attachment dynamics so that probably factors in).
Does it ease symptoms right away?
For me it hasn't. With some stuff, I've had a day or two with crying jags before whatever I'm working on "Desensitizes and Reprocesses." With some stuff, it's taken weeks of talk appointments with my therapist to process and calm enough to EMDR that same "target" again. That said, there's research about EMDR for single traumatic events (car crashes) with otherwise secure people that says it can help immediately. And, I've had two appointments where I ended feeling euphoric and one was EMDR on positive beliefs/successes so it may not even count.
Does lack of rapport / trust / misinterpretations get in the way?
In every therapeutic relationship lack of rapport, lack of trust, or misinterpretations get in the way. I think you're getting at this because EMDR would be with a different therapist than your current one you have rapport with. It's not just hooking yourself up to a machine, granted there's way less talk processing, but this is a person sitting opposite of you and EMDR begins with identifying your targets and creating a safe space/container. There's times where you're asked to focus on the most traumatic parts of your trauma. Feeling safe and having trust definitely helps.
What if you need to talk about current stressors/triggers before processing past stuff? Can you or is that EMDR too?
I do this ALL the time. My therapist says it's not as useful to EMDR on a trauma that is currently active (like if your triggers are work-related bullying and you're being bullied in the current work but planning to leave the job, wait until you've left the job and the trauma and its connection has hit resolution). Plus, talking about triggers/stressors and preparing a container can be a step that lasts a while. EMDR can make you feel volatile so most therapists won't just launch in to it with someone. I generally have at least one talk session between EMDR, and because I'm avoidant I sometimes will try not to use EMDR in a session while I'm talking/processing the same traumatic situation(s). Generally, my therapist just tosses me the buzzers and has me continue talking with the bilateral stimulation. I've read some lit on this too and apparently this is a practiced technique.
Anything else about how it works.
I don't get any visuals, I don't cry in session, and I rarely have my most important processing moment in session, which are all the things I read about that made me think EMDR would intensely blow my mind. That said, I can talk about past traumatic situations and have a pretty even keel emotionally that I didn't have before. I have a bit more grey understanding and less black and white, and nothing I've EMDR-ed on hits me in the same, sometimes-physically-painful way it used to.
If you're interested, go for it!