In addition, apparently methods and spesh are very similar. Spesh just goes into more details. So studying for one is like studying for both (from what people have told me).
Somewhat. I mean, you cannot completely neglect Methods, but they tie in much closer than Methods and Further do. I guess it also makes Methods seem a lot easier, and your general skills will improve too.
Drop it, personally I hate physics too, but I might do engineering so I'm keeping it and drop economics. If your not doing any thing related to engineering in uni, may as well drop it.
You're not necessarily obligated to keep Physics, especially if you do GMA. There are also some engineering courses (such as Monash's ones, from the top of my head) that do not necessarily require Physics if you have Specialist or Chemistry.