92 cents for the 1st class stamps. 40 cents for 2nd class stamps.
15 cents for the general ones.
1 euro
That depends on what you mean by "near." Basically, France is between Spain and the UK. Spain is much nearer to the UK than to Australia, but much farther than France, Portugal, or Morocco.
5 shillings
1 Euro
98 cents
Legally there is no limit.
Free if the dog has wings!
In the UK a standard first class Royal Mail stamp in December 2013 is 60p.
Spain is an hour in front of the UK
Spain is larger physically, and has a larger population than the UK.
To send a letter to the UK, First Class (that's Air Mail,) the stamp costs $1.02.
The UK visa reference number should be contained within your stamp. Every time you have visited the UK, you will have received a stamp. If you had used a visa, there will be a reference number within that stamp.
One could find collectible Australian stamps in the UK on eBay and at stamp collector's fairs. Fairs can be found across the UK on the diaries of Stamp Diary and Stamp Show websites.