she sounds adorable.My kind of pup, cheeky and a bit naughty. lol

Ok problem 1

do you praise when she goes outside?? if she goes inside do you throw her out?? because if you put her outside whenever she goes in the house she might start to think that going inside is the only way to get the door open. you could try training her to ask to have the door opened for her. our rottie has a funny growly noise when he wants a door opening and the ridgeback jumps at the door, that way you know who it is. lol. everytime your dog looks at the door/barks near the door open the door to let her out to encourage asking behaviours. always praise when going outside too.

problem 2

is she playbiting or is there some aggression to it, if its play, shout when she nips then turn around and ignore her until shes calm before you start fusing her again. unfortunatly at that age trainign can take a step backwards, they are getting ready to become teens.

Problem 3

for pulling on the lead you could a harness and put the lead on the front at her chest then when she pulls she will spin round. same idea as a head collar but without the risk of neck injury should she bolt. As for the chewing on the lead your doing the right thing, stop, ignore her until she calms down and them walk again. maybe with some treats once she is calm. how long do the walks last, it may be that shes still go too much energy, mybe extend the walking time or try to feed her a lower calorie food, you could just not feed her till she gets back then she wont have as much energy either.