Hi, and welcome! I hope you will find all the answers you need here. It's a great community. Anyways, in answer to your questions (be aware I'm no doctor and have only recently begun researching all this)...
1) Seems to me like it is. You may have seen lower BP values, both in yourself and others, but thing is, it's far, far easier to faint if the drop is fast. If it's slow, the body apparently adjusts. If it's fast, well, you kind of drop along with it. You might want to try getting up slowly, that seems to be helpful for that kind of thing. Give your body a moment to adjust.
2) Though HR and BP are very closely related, it's possible (in my experience, anyways) to have one go crazy without affecting the other THAT much. See, one thing that can drop the blood pressure a LOT is vasodilation (probably the main BP-dropper, actually). The heart then is supposed to speed up in order to maintain your BP and thus the bloodflow to the rest of your body. My guess is that what causes you to faint is that your heart isn't speeding up *enough* to keep the blood flowing well after such a sharp drop in BP, and that for some reason, rather than constrict the arteries, your body is doing the opposite, hence the sharp drop in BP. This is just a guess, but still. It might suggest to you what to ask your doctor?
I hope the information is at least a little helpful!
Yes, sounds like OH to me. I also have had the drop in BP on standing but only on occasions. Dehydration has a big influence on me. The Doc prescribed 30-40 mmHg thigh high compression stockings to keep the blood from pooling in my legs. They help some as I do not get so lightheaded when I bend over to pet the cat, etc. then stand up.
My resting heartrate was 50 bpm. I had a vasovagal syncope in June & when I feel, I broke C5 & C6 in my neck. I was momentarily paralyzed but then the nerves started coming back online, thank God. When I was released from the hospital with my neck secured, they gave me Percoset for pain. I took two the 1st night & the next morning had a case of OH. My wife held me from falling again. But back to the ER and they then put in a pacemaker. They thought it could keep up my BP. It doesn't. Still have the drops at times. I think the fluids I drink & comp. stockings are what has helped me. I can manage this now and do pretty much my regular activities with these minor changes.
It may also benefit you.