without knowing exactly how you constructed the braid, it's hard to tell what the problem is. did you reinforce the inside with anything? it could be that it's collapsing and not allowing anything to flow through it.
i almost always boil off 1.5 gallons during a one hour boil. so, that matches up with your boil off rate pretty close, which i think it fairly common for a lot of brewers. i know you didn't, but you don't want the lid on the pot at all during boiling. it will affect the flavor because it is a more concentrated wort now. it will have a higher alcohol percentage also, but of course, there will be less of it.
the sediment in your fermenter is called 'trub' and is a combination of proteins, hop debris and other stuff. don't worry about it, it will compact itself into 1 inch or less in no time, you will just need to leave it all behind when you go to bottle or keg or whatever your next step is after fermentation.