As someone who went from a half to a full with a 13 week training plan after a few months of just running I can tell you that the slower and more complete your build up the less trouble you are likely to have after the event.
Try and find out what your weaknesses are too, I wish I'd done some good core strength building for mine as it would have saved me a lot of pain.
This is a constant issue at any race with a decent numbers of participants.
I don't think people are doing this out of selfishness, but I do think many people massively over estimate how good they will be when they reach the line on race day.
I spend every race passing people futher up the pack, in my first half I passed a couple who had started just behind the Elite group. I was estimating a 2 hour finish!
My advice is enter smaller races or you just have to put up with it. You need to find yourself a little space and exploit it, keep an eye on the gaps up ahead and try and stay away from groups of people running together - they are a nightmare to get round.
I did periodically try and run during my recovery. But I'd done a load of damage running 3 half marathons with it being injured. Stupid I know, but I had races to run that completed a target for the year.
The difference with me was that I had weakness. If i tried standing on tip toes on the injured side it was way weaker than the good side. This feeling took about 4 and a half months to go. I actually went to Six Physio to see where they thought I should go next with it.
A bit of massage of the area and loosening up after the long rest did the trick, but by then the weakness had subsided.
Just to say that if that is a genuine Six Physio account, I'd recommend following their advice. I have had several appointments with them and they are excellent. Have really helped me on each occasion. Just thought it was worth a mention.
Depends how much you have damaged it. Mine took 6 months to go away!
Largely depends whether you have just irritated the sheath around the tendon or if you have tears in the tendon itself. Do you have profound weakness or is it just pain due to swelling and poor repair?
Achilles tendons are difficult to treat and slow to heal I'm afraid.