Here's commercial site that might provide some general information for you (Augusta Medical Systems):
https://www.augustams.com/how-to-get-an-erection-on-command-with-a-penis-pump/I'm not a medical professional of any kind. Anything I post is based on my own experiences, at best and hallucinations or delusions at worst. Internet forum advice is very likely worth exactly what you pay for it. Always ask your doctor and follow his/her advice.
#1) I'm not 100% clear on your questions. The VED with tension rings will give you an erection so yes in that respect it will increase your size temporarily. Yes, a VED can also increase your size temporarily over what a natural erection would achieve, given your current condition. I can't give you values as to how much the increase could be. I'm not sure anybody can.
#2) How long does it take? Well, not long. Just a few minutes.
#3) How long can you wear a constriction ring? I've seen 20 min and I've seen 30 min. You should ask your doctor for a competent professional opinion.
#4) How long after you're done could you use it again? I don't think I've ever seen that stated anywhere and I've never asked a doctor that question. I would think the next day for sure. I've taken a ring off and waited just a few minutes and then repumped and reapplied but that sure isn't a medical recommendation as I'm not qualified to make one.
#5) Is there a wait time for the blood to flow back in? Good question and I don't know the answer and like the previous question I never asked and I've never seen it stated. I just kinda winged it. Use common sense and due caution. If you get an answer from a qualified professional let us know.
Good luck!