Travelling in Germany

lizi0205

My husband & I are travelling with our touring caravan down to Bad Birnach, Germany this month along with our friends who will be in a motorhome. We are very confused over the legalities of the emissions badges. Do we need them? Both  caravan & motorhome
are brand new and are similar length 7.5mtres. Also we are hoping to do part of the travelling overnight so are we safe to sleep in our units in the autobahn service areas? We tend to do this in France without charge and of course taking extreme safety measures.
Could anyone help us with choosing the correct badge and also recommend a german sites Guide book.

many thanks in advance.