Do I need a visa to enter Laos as a French citizen?

The Laos visa on arrival fee for French citizens is $30. There may be an overtime fee of $1 if you go after 16:00 or on a weekend. Have a passport photo for this too or they will charge you an extra $1-2. It's best to have all this in USD cash, they will take THB but bump up the fees significantly. You don't need exact change, like if you have $40 or $50 they will give you change in USD.

You get the Lao Visa at the border or even online - check lao online visa

Flying into Laos you can buy visa on arrival for US citizen? All visas require a bank book or statement in addition to showing cash?

...Is this your first Tourist Visa?

...What visa are you now on?

...Where did you get your current visa?

...please read what Amornrat posted about...

VIENTIANE

Tourist Visa, if you had previously some Tourist visas your application will be considered more carefully.

Vientiane is now, in most cases, asking for proof of funds, Book Bank with balance THB 20,000.- up OR print out from Bank account from home country value USD 700.-up.

Onward air ticket is not required.

You need a visa to enter Laos. You can either get it at the Laos embassy in Thailand, or as a visa on arrival at Friendship Bridge. I don't know how much it is for people from your country, but it usually is between $30 - $35 USD, or about 1,500THB. Convert the currency before you arrive, AND make sure they are clean, new notes.

You buy it at the border crossing