If you are talking about a basic trailer like you would get in Halfords, you will not need twin electrics, just the plug to make sure your lights and signals are visible to following vehicles. As for fitting a tow bar, go to the garage that deals in your make of car. They will have the right kit for the job and you will have a better comeback if anything goes wrong, also your insurance company will be happier. The garage will also know your vehicles capabilities regarding the tow train and the maximum weight you can tow safely. Braked or unbraked depends on the size of the trailer you get. There are also restriction on your licence if you have taken a driving test lately.