No you choose the cabin grade YOU want with whom/whoever you buy from. Don't listen to urban myths.
Yes, they make you sleep in the annexe. ... Neil.
Is that the one with the outside toilet .
On many lines you can choose a specific cabin number so the answer is No, and if your travel agent is charging full price I would go elsewhere. Does anyone pay full price nowadays?
It is a fallacy that booking on the web is cheaper. Any good travel agent will be able to match the price and will also give you best advise, It is very difficult to ask the web a question!!The answer could save you lots of money.