Yes policies are available for both individuals and couples.
Theoretically anyone can purchase a policy, but it will be down to the individual insurer that you meet their criteria, certain restrictions apply such as age, insurable interest etc.
Yes. There are many different types of life insurance, the 2 most common being Term insurance and Whole of life, the subject is to vast to cover here and you should talk to an expert before making any commitments.
This is dependent on several factors such as age, sex, if you smoke and the length and type of policy.
Who benefits is entirely up to you, most people arrange it so that their family receives payment, but the beneficiary can be anyone.