Correct mistakes

Can you have a look at the following letters and correct any mistakes, if necessary.

A formal letter:

Dear Sir or Madam,

I am writing in connection with your advertisement for Proficiency Photography course in England that I found in the Daily Telegraph from 23rd March 2012.
I would like to ask about the program of this course and an/the opportunity to receive a certificate for its completion.Can you send it to me?
I am interested in the size of groups and some required experience. Do I have to possess any previous experience in taking photographs? Do you intend to check it ( I mean experience) somehow in practice? I prefer learning in small groups because then I believe will make some progress.
I would like to know more details about the number of hours of classes during a/the day and the total duration of the course. How often do the lessons take place? How long does the course last?
I am still not sure about two things: What is the price of this course? Where do the lessons take place?
I look forward to your answer.
Yours faithfully,

A postcard:

Hi Susan,
I'm spending my holidays in the mountains in Austria.
I'm climbing the mountains and visiting many interesting places.
The weather is sunny, sometimes it rains.
I am planning to stay here for 10 days.
I am going to return to Paris little relaxed. After my arrival we can go out and go to the next any good place.
How about your holidays? I hope you're having a great time, too.
See you soon,

Thanks in advance for your help

layla