Handling companions is tricky business and it is always advisable to go into town to the Holding and Confinement facility to get them identified, sell them or have them bound to you. Healing in general is handled by the Guild hall. If, however, you have the unfortunate event of death it's not all that bad. Other players can search for dead characters and go and retrieve them and bring them back. All of this adds years to the age of your character.
Characters only live so long, each race having a specific life-length.
My Yeti is in sad shape, being the first character. He died quite often and although starting out at 16 years of age, is now 35. And, Yetis only live to be 175 years approximately. Yes, your character will eventually die of old age. Also, he lost quite a few constitution stat points when complications arose in the resurrection process.