The following site will give you good info on your queries.
It is populated mainly by brits retired to France, many of whom run Gites businesses. The are in a very negative place right now because of the weakness of sterling v. euro.
The main difficulty with investing in France as far as I can see is the astronomical transaction costs. Capital appreciation has generally been very sluggish. So you really want to be in it for at the very least 5 years and ideally 10 - 15 years. Capital appreciation in Brittany was 6 % 05/06 for example.
I bought a good book called "Buying a home in France" By David Hampshire...suffice it to say after reading it we decided to rent!
I suggest you buy it and read it before you commit to anything
The various fees/taxes can amount to anything between 26 and 40% of the quoted purchase price of the house depending on its age and other factors.
If you do decide to creat a holiday home I would suggest that you market within France as well as to Ireland/UK. The french are not great travellers and generally (87%) prefer to holiday in France. Therefore a good market to tap.