Just to add to what Andrew has said - your rates of taxation will very much depend on the source and type of income (earned, unearned, overseas etc ) and whether or not it has previously been subject to any deductions outside of France. Andrews examples are based on earnings generated in France either salaried or self employed. The situation is very different as far as foreign earned salaries, income and investments are concerned. Nevertheless - social charges are likely to form the bulk of your liabilities based on the income figure you’ve quoted.
As you’ve been here some time - you will already have been allocated tax reference numbers which can be found on your Taxe d’Habitation and Taxes Foncières bills. You first income tax return/s will be a manual / paper one which you can pick up from your local tax office or print off from the www.impots.gouv.fr website. You will also find tax simulators on the site which will give you a ball park figure. Technically - you should have made your first declarations in May 2016 on a prorata basis.
As for social security numbers - yours will most likely be allocated by your local CPAM when your register / ed (something you should have done after 3 months residency!). The fact you have private healthcare does not absolve you of the need to register.