OK, this is the blind leading the blind, but I'll have a go!
1) There is a clear-ish bag of liquid which contains the lamb. Before this bag appears, you can get one or more dangly red bags. I have no idea what they are, and am glad you asked!
2) I don't know - in six years, I've always managed to get them out the same way they went in. Just be assured that C-sections are not all that common. I guess if a ewe is struggling with a very big lamb, or if she hasn't opened up properly, that could require a C-section. However, again, I'm glad you asked, as now we'll get to find out!
3) Yes. Usually a backwards lamb will get stuck coming bum first. Check for tail, and the direction the 'wrists' bend, so you definitely know what you're dealing with (try that on a newborn - front and back legs bend different ways and have different, er, elbows). Then, push the lamb back in, cup back hooves in your hand and bring them up and out. Then pull in a downwards direction. Once you start this maneuver you don't have long, so brace yourself and get on with it!
4) Depends on why I had to assist. If it was due to a leg back etc, there's no reason why subsequent lambs wouldn't be born naturally. If you were lambing hundreds in a barn you'd just deliver the others and move on to the next sheep, but as a smallholder you don't need to be so efficient, and can let things happen naturally. I set a timer for 30 minutes in between lambs, and if there's progress I leave alone. If nothing has happened after that time, I might go in in s minimal a way as possible, just to check all is well.
HTH!
>Feel free to add your own questions!
5) We have a ewe who has bitten tails off her newborns for two years running. She would have been mutton by now, but life is complicated, so she's being tupped again. Any ideas how I can stop her this time?