1) No degree/Diploma credentials are required, but yes If you want to feel more secure in claiming the points of areas of training or you have some doubt either you will get full points or no for your education, then you can go for credentials which is called evaluation for the studies done outside Quebec. Its official fees is 112 CAD
2) As per the present rules no compulsory stay is required in Quebec, but morally you should first try to find your employment and try to settle your life there and if you fail and you have employment opportunity in other province you can definitely move. Two of my friends have settled in Ontario after getting visa under this category.
At the time of the citizenship you just need to explain your reasons of changing the province. If you have legitimate reason of employment or so on there would be no problem in that.
But yes Quebec government is thinking to bring the law imposing compulsory stay of one or two years after landing to avoid these things.
3) It is not mandatory to file the csq application with the job offer of Quebec, if you are meeting the points criteria you can submit your application. But if you do have the valid employment letter it will give you extra points and make your application speedy.
Generally it takes 1 to 3 years from India, depending on profile and the High commission, yes it is the time consuming thing especially if you are applying from India.
4) French is one of the important factor for selection and the processing. Without french there are every chances of slow processing and so on. French is definitely given the preference and people with Intermediate and Expert level french can expect their processing fast and expect the Csq without Interview also. Without french definitely you will have to wait for your turn in the interview if you are meeting the points criteria then also, then if you are able to please and convince the interviewer that you can do well and establish yourself in Quebec then only you will be awarded the CSQ.
Application and Selection are both absolutely different things. The selection process and the points assessment for the selection lies in the hands of Quebec Immigration. So to be selected from India, you need to have grip on french which should be supported by the relevant documents. The proficiency of the french language will give the immigration officer the intention that this candidate is due to settle in Quebec and he can find the employment there easily. Means he needs to mark that you will be able to adapt in the quebec atmosphere, which is also important aspect of the selection