YES (with the owner's permission)
Yes you don't have to have a licence of any sort to have a car registered in your name. You are just not allowed to drive it alone if you don't have a licence.
I believe you are allowed 7 days on your bill of sale to get the car registered.
The vehicle must be registered in order to be driven on public roadways.
NO!
A car can be registered and insured by a number of people. Usually they are one and the same. A car can be insured with having it registered to you if you would like to drive it.
It isn't YOUR car until you have paid the lender.
yes
There are no restrictions on left-hand drive car ownership in the UK. All foreign registered cars do have to be registered with the DVLA, with the exception of EU nationals driving EU registered cars for up to 6 months.
15 or 18
yes
Yes. If your name is on the registration of the car, you are considered to be in control of who is allowed to drive it, therefore, you are held legally and financially responsible for everyone who drives your car. Many insurance companies do not cover drivers other than the registered owner, should an accident occur. This is why it's wise to be very, very careful of who you allow to drive your car.
You can sell the car with expired plates. You just cannot drive it.