The purchaser pays the estate agent fees. Find out from the agent how much. If the house is with more than one agent the fee may differ/be negotiable. We were pressurised to sign by the agent.
Having said that the agent should know of local tradesmen. Ours organised the "devis" for some roof repair work. But, wash my mouth out with soap, I felt on another property that the agent would receive a commission.
In theory the local marie should be able to provide contacts for local tradesman. The practice might be silence.
ArtisanExpert may help. As per advice on other threads try and obtain several quotations. Beware the "English" price.
If there is time, a local architect will have a feel for converting "modernisation" plans into budget using local artisans, and they should know when (particularly energy efficiency) grants and tax reductions are available.
In my own experience do not expect good communication (2 of 10 architects replied), nor speed. It took the immobiliere more than three weeks to get the carpenter/roofer on site to prepare the "devis"
"Google" will find reputable reports on the state of the market (broken down into geographic regions) , the market generally fell by 1%, but is bouyant in e.g. Bordeaux.
The Drome/Vaucluse is popular with other continentals. The Ardeche on the other side of the Rhone is slightly cheaper.
If you proceed you will have an experience opening a french bank account. Again follow advice in other threads and register with a currency brokers. There is no rhyme or reason to the fluctuations in the currency markets, but estimating a total budget of around 500M the currency savings are considerable. My broker transferred the euros direct to the notaire's client account, and no charge, whilst some banks might even charge on a percentage basis.
Finally, consuming lots of garlic might strengthen your resolve. You will need it if your experiences are similar to my own