You will need space to walk and for your feet if you turn the chairs around - if you put a divider in you will block the view from the dining table out to the balcony - and thus make the kitchen and dining room both have no view ! So if you keep it open, the natural light can get through !

Chesterfield looks great with exposed brick walls and/or wooden flooring. Of course the classic aged brown leather is popular among mature users but the room has to be big enough so that the sofa becomes the focal point.

which type of sofa I should buy ? m confused

I think you need to ask yourself some more questions. If you have children - get something that can be cleaned easily. If you have pets that get on the couch - again, get something that can be cleaned easily. Do you want a sofa that can convert into a bed? How humid is your climate - think of the upholstery and possible mold/mildew if the sofa is not in a location where there is good airflow. If you live in a dusty climate, find one that can be wiped or vacuumed easily. MY first consideration is if the couch is comfortable to sit on!