1- i decide to choose free range to minimum the budjet and get organic eggs
I'm not sure what your weather is. By latitude you are close to the center of the US but you may be on the coast. The presence of water can make the climate pretty mild. That will have an effect on how much nutrition they can get from foraging. A big effect will also come from rainfall, I think of Algeria as having a wet and dry season but I've never been there.
The bottom line is that the quality of your forage will have a huge effect on how well this works to reduce feed costs. If they rely only on forage there is a pretty good chance the quality (mainly size) of the eggs may not be great. Since you mention females I assume this is for eggs, not meat. I think there is a good chance you will have to purchase additional feed for them, at least for part of the year. There are trade-offs for everything.
I have no idea what kid of market there is for "organic" eggs or what constitutes an organic egg in Algeria. To success in a project like yours you may need to find a niche market, have some type of advertising gimmick that people are willing to pay extra for your eggs. Organic, free range, or cage free are often used here.
2- confuced to buy a 100 female or raising a flock from 0 ( alot of chicken diseases on my country )
I don't know which is better for you. I don't know what breeds are available. If you buy started pullets the cost can be pretty high per bird. If you buy baby chicks the cost per chick isn't too bad but you need facilities to raise them. Or perhaps you could get hatching eggs and an incubator to hatch your own. Of course, if you hatch your own or even get baby chicks just hatched how do you sex them? What will you do with the boys? Raising for meat is an entirely different business than producing eggs.
One huge issue is disease. You need to read up on biosecurity. The commercial chicken industries over here have very strict biosecurity practices. If you hatch your own eggs you can control biosecurity. If you get just hatched chicks you need to see their biosecurity. If you get started pullets you are much more exposed to bringing in problems.
One problem you have with eggs is that chickens got through a certain cycle. They typically produce as well as they are going to their first two laying seasons. Then, after their second adult molt production starts dropping. The commercial egg laying operations over here use specially bred chickens. They experience a drop of maybe 15% to 20% after their second adult molt. That's enough of a drop for them to not feed them through a molt but to replace hem with another flock.
Another issue is that chickens go through a cycle of laying well in the good weather months but when the days get shorter in the fall they stop laying and use the nutrition they are eating to replace those feathers. So you get a lull in egg laying in the fall and winter. Your customers have to do without, not good for long term contracts. The way they handle that over here is to house them where they can control lights to stop them from molting. If yours are foraging you can't do that. I've simplified it some but this natural cycle of laying may be a huge issue for you.
3- whats the best way to feed or raising them
I believe you are talking about baby chicks. Not sure what is available to you.
4- is it any profit of that or just wasting time
That is the big question, isn't it. What is your competition? Where do people buy eggs now, who supplies them? If you are up against big commercial operations with an established supply chain for what they need and especially using the commercial hybrid layers it will be almost impossible for you to compete unless you can find a niche market so you can get established customers willing to pay a higher price. One possible customer might be a specialty restaurant where the chef can tell you how he wants his eggs produced. People do this kind of thing but it is not easy. But starting any business is a challenge and people try all the time. Some succeed.
Good luck!