I had preclampsia when I gave birth to my daughter. I never had to do the urine testing though because my bp was wierd and would spike only sometimes and protein was never found in my urine until the day before I gave birth to her (they induced me because of it). I understand your concern, it's a scary thing to think about.
Signs of preclampsia would be headache, feeling faint or dizzy, high blood pressure and severe swelling in your ankles and hands. It's important to watch for those signs even if you are feeling ok because your body would not be ok and you'd need to get to a doctor asap.
My advice is to take your doctors advice, get your bedrest and don't stress over it. Reading about it on the internet is only going to scare you and make your bp rise lol so don't do that. As long as you're being watched closely by your doctors and are being careful to take their advice you will be absolutely fine, so will your baby. Get educated about it through your doctors and nurses.
Another thing you can do is do a no salt or sodium diet and up your protein intake. It's VERY hard to find foods so low in sodium but it's not impossible and it will help you. Drink LOTS and LOTS of water and stay off your feet as much as possible. Sleep and rest lying on your left side, it helps to keep bp steady. If you feel faint or headaches, dizzy, anything like that or your hands and ankles begin to swell more than normal call your nurse. It also helps to watch your bp at home if you can too, you can buy a home bp kit or go to a public bp station a few times a week to check it.
I know all this is scary but don't worry, your doctor will take care of you, just follow the instructions they give you. The urine test is only to show how much protein you are giving out in a 24 hour period, if it's too much they'll watch you even closer and give you further instructions, possibly set a date for induction or c-section if needed. ***hugs***