Hello ylarque,
First off, on behalf of the entire Expat-blog Team welcome on board. I hope your experience here will be both informative and enjoyable.
I will try to answer your questions as best I can and in the order you've posed them.
1. Ask for a raise - Without knowing your line of work and a ballpark figure of what you are currently earning that's a tough nut to crack. All I can say is that middle management jobs here in Brazil pay around R$7.000 per month and up.
2. Ask for a better position - Certainly if they want you to move here and assume other responsibilites this makes perfect sense. Even if it is only an upgrade in title only and doesn't come with a higher salary, you're still up a rung or two on the ladder of success.
3. Ask them to pay for a house in Brazil - Living alone or bringing your family here with you? If you're living alone it wouldn't be out of line to ask them to pay for the rent of an apartment. They may balk about the cost of renting a house if you're bringing the whole family here, but they certainly may agree to pay part or all of that too. It doesn't hurt to ask them.
4. Brazilian labor laws require companies here to pay their employes what is called "13° salário" it is essentially a pre-Christmas bonus equal to one month's salary (prorated if you've been working for them less than a full year). I'm not sure, but maybe they may be obligated to pay you this by law.
5. Keeping French holidays - Sorry I don't understand, are you talking about vacation time as opposed to holidays? They are different. Holidays are days declared by the government of a country as special dates and people don't generally work on those days.
Vacation time - by all means, tell them that you won't even consider giving up any of the vacation time you've earned with them during your employment.
Holidays - don't beat a dead horse, we've probably got more holidays here in Brazil than you would imagine. You will have more than enough days off with the Brazilian statutory holidays, trust me.
6. Ask for a car and driver - Again depends entirely on your position with the company and if a car is essential to your function. If so, a car and driver are almost essential and here quite common with foreign companies. Brazilan drivers are among the world's worst so you wouldn't want to risk driving yourself. Besides that the bureaucracy of getting your foreign license recognized here is absurd and you can only use it for 180 days. Beyond that you need a Brazilian 'Carteira Nacional de Habilitação" and that's real tough to come by.
7. Ask for a flight every so often to return - Forget the idea, if you press your luck too much you could end up putting the torpedo to the whole job offer. If you want to come back for vacations it's worth footing the bill yourself.
8. Leave your flat and ask the company to keep your stuff in a warehouse - If they have a warehouse and could store things where they will be safe, protected from the elements then maybe they would be willing to do so. If they don't I wouldn't even bother to ask. Again, this could Scotch the whole deal altogether. If your stuff is all top quality and brand new then I'd suggest putting it out 'on loan' with members of your family provided they are aware they must take good care of the things. Otherwise if you haven't got a lot of stuff I'd give most of it away. You'll have to buy things here, shipping your stuff is just too darned expensive so forget that unless the company offers to pay for that.
9. Anything else specific to Brazil - Yes, LANGUAGE TRAINING!!! While English is widely used in global business the operating language here is and will always be Portuguese. You will also need a reasonable level of fluency just in order to survive daily life situations. Get an agreement from the company that they will pay those costs since it will be in their best financial interest.
Hope that the foregoing has given you lots to think about and ammunition for the negotiations.
Cheers,
William James Woodward - Brazil Animator, Expat-blog Team