1) Probably. If you do have some degree of a stricture or stenosis, LIS should help with that, and allow for thicker stools to pass. For more severe cases, anoplasty (flaps) are typically used to provide more tissue to let the whole thing stretch open better for a BM.
2) I think swelling is just from the trauma of the incisions. Some people have more than others. I didn't have much after LIS at all honestly. You can get aggravated hemmies or tags I guess, not really sure.
3) Usually surgeons will remove the sentinile tag because it allows for better healing I believe. They kinda scrape out the fissure, getting rid of the old tissue, and I believe this includes the tag too. I don't know about the hemmies...it's really up to your symptoms and the whether the CRS thinks its necessary.
4) I stopped eating at midnight before, as per my instructions. I know what you mean about the nerves, happens to me too. Just follow your doctor's instructions on prep and don't worry about the rest. I never asked this, but I'd imagine that if they stick in the retractor and find a BM waiting to happen they just suction it right out. You can ask your surgeon this to confirm if you want, but I have been in the same situation many times and never had a problem. Being so nervous, I always kinda have that urge as I am heading into surgery, it's impossible not to be so nervous. Also, with LIS, you are not getting stitches or flaps that are delicate and need to be left pristine for a time. You're wound is usually left open, as is the lateral incision (usually). Even if they were stitched closed, a same day dump, i.e. a few hours later that day, wouldn't ruin anything. It might be bloody as all hell, but it's not like you are going to cause damage. Since the LIS is just really snipping the tail end of that muscle ring, you can't really ruin it the same way you can damage a flap.
5) No. You do not need to be in in 24/7 excruciating spasm for LIS to be effective. It could just be that you have a high resting pressure that is not allowing your fissure to heal, even when you do not feel those dreadful spasms. Also, as you mentioned in section 1, if you have some degree of stenosis from the banding, then LIS can also help alleviate that.
6) My doctor did. 2 small fleet enemas a few hours before. I hate to say it but I had so many surgeries and instruments in my butt that it doesn't even phase me anymore.
7) Yes, but weirdly, they did not hurt as bad as before. You're anus will be offended of course after surgery, but the appox. 1 cm section of the IAS that would be clamping down on the surgery sight is clipped, and therefore incapable of squeezing. The rest of your IAS will surely squeeze as well, but that part is not squeezing onto your fissure, so it shouldn't hurt as much. People are different with pain though, so you'll have to see how you feel to decide on meds. For LIS, I did not take anything. Some people take perks or advil though. Get the meds your doctor prescribes just in case you need them in any case.
Water. Sitz bath and a squirt bottle. No wiping for a while. The sitz baths that you buy at CVS actually come with this bag that has a little spray hose attached... that's what I use. but stick with what works. I just stick a piece of gauze between your cheeks till the oozing/blood starts to let up. I had flap surgery 33 days ago and I still got a piece of gauze in my butt as a I type this...
9) I didn't have a choice. I couldn't poop right because of my stricture and I had at the time very severe fissures. I guess, like you, I just could not live with it and had to try for a way out. I was very nervous though, and my anesthesiologist gave me drugs to calm me down as soon as he saw me for that operation. Maybe they'll do the same for you.