Probably.
You do not need a pasport but you do need photographic identity.
Check with the airline.
Nothing else.
You can't fly directly. It would have to be Sacramento to LA. LA to London. London to Edinburgh. Edinburgh to St Andrews by bus or train.
You do not need a passport to fly from London to Newcastle-upon-Tyne, as both locations are in the UK, however it is always best to take your passport with you just in case.
You can't take a train directly from the Shetland Islands to London. You can't even fly directly between Shetland and London. You could travel by boat from Shetland to Aberdeen and then take a train or fly from there to London or you could fly from Shetland to Edinburgh and either fly or take a train from Edinburgh to London.
Yes, always.
No you need a passport.
No, however easyjet does from Edinburgh, Manchester and London-Gatwick.
It is regarded as an internal flight, but you should bring a passport with you any time you are flying.
* KLM fly to/from: Aberdeen, Birmingham, Cardiff, Durham Tees Valley, Edinburgh, Glasgow, London (Heathrow + City), Manchester, Newcastle, Norwich. * EasyJet fly to/from: Belfast, Bristol, Edinburgh, Liverpool, London (Gatwick, Luton and Stansted) * Aer Lingus fly to/from: Belfast * BMI fly to/from: Aberdeen, London (Heathrow) * bmibaby fly to/from: Birmingham, Cardiff, East Midlands * British Airways fly to/from: London (Heathrow. Gatwick and City) * Flybe fly to/from: Exeter, Southampton
Yes, you can get a one day 'tartan visa' (similar to the visa waiver program) when you land in Scotland.
Although both Greece and UK are in the European Union you still have to show an up to date passport in and out of both countries.
The major airlines that offer flights to Edinburgh are United, Virgin Atlantic, Air Canada, British Airways, and Delta. The airlines listed will vary depending on which city you leave from.