If we're talking pistol bullets only, then by and large anything that will pass the NIJ .06 level IIIA testing protocol will work. No need to go armor plate. This is pretty much the standard for most LE soft body armor these days. Now the NIJ .06 testing protocol does not address every round capable of being fired from a handgun (a TC in .30-06 for example), but it does address the VAST majority of the stuff an LEO is likely to see. The N. Hollywood shootout, basically was the result of the bad guys doing what you're thinking of, they just used surplus vests to wrap around themselves. It worked pretty dang well. There are companies who make armor systems that are similar to what you're discussing, IIRC they weight in the 60 lb range for a full body head to toe setup. With a lot of that weight being in the ballistic visor for the helmet. A bombtech suit is pretty similar, but it is tested with a different standard so it's not technically "ballistically resistant". These setups when done professionally use an internal harness to hold it all in place, distributing the weight much like a good camping pack does. It is tiresome to run in, and the arms do get heavy after a bit. They are also stupid hot, and don't breath at all.
If you want to talk shields, a large pistol rated ballistic shield (40"-48" in length) usually runs around 30-40 lbs. The viewport is actually the heaviest part of the whole shield, so that's why they are either tiny, or the shield is stupid heavy. That's why you rarely see rifle rated shields with viewports if they're man portable, as the viewport weighs about 1/3-1/2 lb per square inch IIRC. Over in Europe they like using semi-rigid or completely soft ballistic blankets, and then having a ballistic visor. You trade off a little coverage area, and save a lot of weight, but add some of it to your helmet.
The 5'-6' rolling of whole body shields are usually above 50 lbs, but these are pretty rare anymore.
Adding a light, which is a necessity really depends on the company. Safariland makes a great light kit in terms of output, but it might as well be a pair of car headlights and a 12 volt battery for the weight.
Up until this past December I was a full time LE firearms and tactics instructor, and terminal ballistics and armor fell under my purview as well. I'll be happy to answer any questions, thought nothing OPSEC of course (which considering almost everything materials related is all open source, there's not much to worry about there).
