Well, if he only goes into his cage to eat and/or sleep, the size is not that important but you have to make a place for him where he would be comfortable. Use tree branches (make sure the wood is safe for him to chew on -not toxic- and that the trees have not been sprayed with chemicals. Don't make the branches into perches, use them as they are (crooked and with little branches coming off the larger ones) like this:
http://www.bing.com/images/search?q=Par ... ORM=IQFRBA but you don't have to make a stand, you can simply attach them to the outside of the cage with rope (he will chew the rope so make sure it has not been treated with anything, too). You can also hang rope with knots from the ceiling so he can climb up and down. He needs more entertainment than just a square cage with a round dowel in it. To get him used to the wood, just leave the branches laying around not too near him and put them closer and closer to him when he doesn't show any fear of them until you can attach them to the cage or make them into a stand.
As to food, yes, it's hard to find good bird food in countries like yours (I come from South America so I know) but you can improvise. See if you can get wheat, barley, millet, sorghum, oats and brown rice in the market. If you can't, see if you can contact a mill (where they grind the grains into flour) or farmers that grow the crops. Cook them until they are softer but not completely soft (the grains should remain whole and a bit hard -that's they way they like it best) and mix them with cooked lentils, beans and lots of vegetables like carrots in small pieces, corn, peas (if you can find any), green beans, cooked sweet potato (very important for the vitamin A which they need), broccoli (or some other green you can cook like kale or chard (but try not to use too much spinach), peppers of any kind, squash or pumpkin, etc.
Lebanese cuisine has bulgur (which is cracked wheat), lentils, peppers, garbanzo beans, chard, flat green beans and I've seen recipes with sweet potatoes, white potatoes, garlic, cauliflower, squash, tomatoes, cabbage, etc. all things you can use. You also use a lot of eggplant but I don't feed it to my birds so I don't know if you should. Ahhh, and no onions, coffee, tea (unless it's herbal), anything with alcohol, avocados, chocolate, fried food, meat or any other animal product, salt, sugar. Basically, when in doubt, don't feed it.
You also have figs and dates which my birds love and are very nutritious. Oh, and walnuts and almonds, you have those, too!
See if you can find a seed mix for smaller birds (like canaries) and mix it with the sunflowers (too many sunflowers is VERY bad for their liver), if you can't, see if you can find some canary seed, millet, safflower, sorghum, quinoa (I saw a recipe that uses it so it must be available somewhere).
If nothing else, give him a piece of multigrain flat bread, it's better than sunflowers.
And don't allow him to get into your mouth, humans have bacteria that is only for humans, not birds and they get sick from it.