I have left France 5 years ago, but the following should still hold:
[Boursorama Banque] (https://www.boursorama-banque.com/?origine=2403) is among the cheapest french banks. It is totally online and for a normal usage it should be absolutely free to use. (Check their conditions if you have fancy requirements)
Free.fr is by far the cheapest: depending on your needs you can have:
Health insurance is directly taken out of your salary, so you won’t have any choice. I don’t expect you to need a car in Paris, so you will only need a mandatory insurance for your apartment (which usually is as well a liability insurance). You can use an insurance comparator like https://www.lelynx.fr/ to compare them but usually this is really not a big expense.
As you can see, all these topics are a tiny fraction of your income.
Except for the health insurance: although it is not a “direct” expense, you will still have 8% taken out of your brutto salary for your health coverage. There will be as well 15% of your brutto salary taken for the social contributions (i.e “CSG/CRDS”), which don’t provide any coverage, but are a mandatory contribution to reimburse the french social security debt.