Hello,
1. Correct:)
2. While in France you will use: 00 1 ??? ??? ???? to reach US phone numbers.
3. France cell phones are 9 digit and start with either digit six or seven. In the beginning however there is a zero when dialing within France: 06?? ??? ??? or 07?? ??? ??? (so 10 digits total). This is what you will dial.
4. Same rules above apply for calling French landlines: 0 followed by 9 digits (although the first digit after zero isn’t six or seven anymore). France has a closed numbering system which means that they do not use area codes. In other words, you will dial the same number across France.
5. People in France would call you as if you were in the US: 00 1 ??? ??? ???? (they might not like it since international charges apply).