trailer questions

[horsehound]

We bought a trailer on ebay recently and I have two questions!

First, do you just hook them straight up to the tow bar or should there be some sort of safety connector thingie in case it disconnects while travelling?

Second, ours is an unusual size (4.5ft x 3.5ft), where is best to get a cover for it? We have a cheapy tarp but it will need to be doctored a fair bit to fit - is it worth paying out for a made to measure cover or should I stock up on eyelets and duck tape?

Thanks for any advice!