I was always under the impression that you use SECAM in France. What's the difference here compared to PAL/NTSC? I really need to read up on this stuff more.
http://www.diffen.com/difference/NTSC_vs_PAL
https://en.wikipedia.org/wiki/PAL#PAL_vs._NTSC
The main difference is that PAL is higher resolution but slower refresh rate. I don't live in Europe but from what I understand a lot of modern HD televisions have some compatibility with NTSC. Be sure to check the documentation of your TV. If you're using an old CRT display it won't be able to render the signal.
If you can read french I've written
a quite lenghty post on the subject
The specific case of SECAM was a thing in our territory during 80's but most of Hi-Fi hardware was already supporting PAL signal at the start of 90's. When third generation gaming consoles released in France PAL was already a standard for video equipment, SECAM became mostly a TV broadcasting only technology, VCRs and such did support SECAM sorely to be able to record TV but everything was PAL video output and RGB encoding.
I've read up a little about the Famicom and the 1st version doesn't have composite video out: Only RF cable, that outputs indeed NTSC signal..
Seems that the original japanese RF switch is a very strange beast where you had to connect the wires
DIRECTLY - R.I.P. Iwata-San - to your antenna UHF receiver:
That probably means the cable shown in my previous post won't do for this console.
In theory as
badATchaos is suggesting the US NES RF cable works with the japanese model and already has a coaxial output so it may save you the trouble of dealing with this prehistoric cables, or you may buy/mod a cable that converts them to standard coaxial..
Though being a NTSC signal that may not be well supported by a EU CRT TV, even though most of EU color televisions support PAL60 through SCART, allowing them to decode video signal from NTSC consoles, I don't know the results with the antenna input, I never tried this.
I suggest you read up and ask more details there:
http://www.famicomworld.com/forum/Personally if I wanted this specific model of
Famicom I would consider the RGB modding and plug this with SCART!
For the power supply I see that the Famicom doesn't have the same characteristics than the NES so I highly recommend
using the genuine japanese power supply on your step down transformer, don't use a US one. If your transformer is set to 100V/60Hz and you use the JP power supply it will be fine.