who is the composer of the above mentioned hindu epic?
It is traditionally ascribed to the Maharishi Valmiki.
Ramayana
The epic, traditionally ascribed to the Maharishi Valmiki, narrates the life of Rama, prince of the legendary kingdom of Kosala. 
what is the relation between kuber and ravan in mythology Kubera is described as the uncle of Ravana in the "Mahabharata". what is this former one worshipped for? He is worshipped as the god of wealth. what significance it has in other religion? In Jainism, he is the attendant Yaksha of the 19th Tirthankar Mallinath. is he a good deity according to the puranas? Yes, as The "Purana"s grant him unquestioned godhood. who is the above mentioned latter god? A king of Lanka and the chief antagonist in the Hindu epic "Ramayana" and its adaptations. where was he born? There are several beliefs, but the people of Bisrakh village in Uttar Pradesh claim that Bisrakh was named after Vishrava, and that Ravana was born there. is he a follower of lord shiva? Yes how is he related to linguistics? He is the composer of the "Ravanabhet" and "Ravaniya". and any medical connection? He is also the composer of the 16th century C.E. scriptures "Nadi Pariksa" and "Nadi Vijnana" on knowledge about the veins. what service did he provide to lord vishnu? As gatekeeper at Vaikuntha. what is this last thing you mentioned just now? It  is the celestial abode (dwelling) of Vishnu.
wiki:11583260
Ramayana [SEP] Introduction
Ramayana (; , ) is one of the two major Sanskrit epics of ancient India, the other being the "Mahābhārata". Along with the "Mahābhārata", it forms the Hindu Itihasa. The epic, traditionally ascribed to the Maharishi Valmiki, narrates the life of Rama, prince of the legendary kingdom of Kosala. The story follows his fourteen-year exile to the forest urged by his father King Dasharatha, on the request of Rama's stepmother Kaikeyi; his travels across forests in Bharath with his wife Sita and brother Lakshmana, the kidnapping of Sita by Ravana --the evil king of Lanka, that resulted in war (against evil); and Rama's eventual return to Ayodhya to be crowned king amidst jubilation and celebration.