If the 150 has an auto tranny, get the biggest cooler that will fit and have the fluid changed before you leave. Cheap insurance. Keep it out of overdrive, even with the empty trailer. Because of that, you are going to have to keep the speed rather slow. Just because you can get it up to 80, does not mean you can control or stop it. If I had to guess, 55mph or slower. Any hill is going to hurt you. Just use the slow lane and if it really sucks down the speed, use those flashers. They won't make you go any faster, but they will help those going 70, realize that you aren't.

The bottom line is that you will be towing on the envelope. No matter what the actual specs are, you will be working with little head room. Personally, it is not a tow I would want to do, unless it was an emergency. But, you have to use what you have available. I believe that the brake thingy you are talking about is a trailer brake controller. If the trailer has electric brakes, make sure that it is the controller. If it isn't, you will need one of those too.

As for binding it to the trailer, you only really need chains front and rear, plus a binder to get it all tight. Straps are a PITA. Nice on the adjustment, but I would not trust them. I only use a strap to keep the body from flopping around. You will not have to worry about that much on your new find.

Good Luck,
Michael