Wills and Estates

My grandfather executed his Will last year in which he bequeathed his apartment in downtown New York to me. After his death a month back, a person approached me saying that my grandfather had entered into a contract to sell the apartment. He has copy of the contract with my grandfather’s signature. I found a copy of the same contract in my grandfather’s safe. Will there be any problem in me inheriting the apartment?

My uncle, who is in the armed forces, was killed in a recent combat. The military sent a handwritten will with my uncle’s body which contained his signature and was attested by two of his subordinates. Is such a will valid?

After my grandfather’s death, we found a will in his safe. The will is signed by him but is not attested by any witnesses, is the will valid?

My grandmother left equal shares in her property to me and two other cousins. One of them had gone to Russia 4 years back. Six months after he reached Russia, we stopped getting calls from him. Our family has been trying for the past three and half years to trace him with the help of police and private detectives, but did not get any information about his whereabouts. What will happen to his share now?

My grandmother left a legacy of $100,000 to me and my brother. The will stated that it was to be shared equally between us. However, during her lifetime, my grandmother had advanced $10000 to my brother. I personally saw her giving him the money but there is no written record indicating the same. Can I claim a higher share in the legacy?