Dont worry folks i deleted the entire thing.. out of it's 30+ modules I am interested in using only 3 and a half..
"1. I tried changing the currency from $ to £ in every field I could find which although I saved the layout, in preview mode everything is in £, when I print or email an invoice it shows in $ again"
If it changes from preview to print, then you must be previewing the layout on which you changed the format of the curency. But when you hit the print button the file is probably being very clever and flicking seamlessly to another dedicated print layout, where you haven't changed the currency format. Does the hardcopy look exactly like the preview?
"Why when you install it can you just not choose your location and currency and be done with it?" - because you may want some fields in $ and some in £, for example. To change them, just click (or shift click to change many) and select Inspector ->Data, and at the bottom you can change the currency format.
"2. I also cannot find where to enter my own company name and details so that they appear on the invoice either." There is probably a Preferences layout wher you can do this. I assume you are using a solution pre-installed with Filemaker, but you don't say which one.
"3. I have no clue how to import the contacts from the Apple Address book either as Filemaker seems only to be able to import." Which formats are available from Apple Address book? I don't use a Mac, but this article http://www.apple.com/downloads/macosx/productivity_tools/exportaddressbook.html suggests you can export as csv, which FM can import happily.