Sure you can reprogram nanites on-the-fly. There's no hard numbers on how long it takes to produce nanites, but the buzzer mentions that an attached specialized nanohive can produce another hive in an hour. And you can set them to damage organics. They're not necessarily the most efficient way to hurt people (that's what bullets are for), but there's no reason you can't. The only thing that keeps them from pulling grenade pins is that they're too small to do so quickly enough. Microdrones are TINY. Width-of-a-human-hair tiny. Yeah you could load nanites or microbots with explosive - Arenamontanus's website has an idea for a swarm loaded with explosives that can act as a super-thermobaric bomb, which is an awesome idea. You could also have them amass into a smallish bomb. Presumably with enough skill you could program them into a shaped charge that could do an awful lot of damage. The problem I see is programming them to seek out the reactor - I'm not sure how smart Nanites can be as far as 'go find x'. The other problem is they move SLOWLY because of their small size. You pretty much have to release them in the same room as the target or it's going to take forever to get where they're going. The hard answer is you can do basically anything with nanobots. The only real limiting force is that they can do anything incredibly slowly. They can do anything, but they're always the least efficient method. An idea I had is a teddy bear loaded with several gas grenades to spray nanoswarms to protect a little girl. One injector swarm programmed to inject everyone within 20 yards except the little girl with Nervex (and to constantly reinject anyone who has medichines), one disassembler swarm to eat everyone within 20 yards except the little girl, and a protean swarm to use the disassembled remains of all the people nearby and whatever else they need to build an armored survival pod for the little girl. Somebody with multitasking or mental speed augs could specially program a swarm in the first round of combat, toss a splash grenade loaded with said swarm at the bad guys, and then join in the fight. Engineer swarms could weaken the floor or walls (SLOWLY, but it could count); disassemblers could eat their armor and then their faces; injectors could, well, inject them with whatever terrible shit you can imagine; saboteurs could break their robots and whatever electronics they were using; basically you can do whatever you want (and whatever your Programming skill and their very slow speed will allow). Proteans are really only useful if you absolutely can't get your hands on a fabber or CM, which is pretty rare. And you can't make a self-replicating nanoswarm, but you can buy a generalized hive loaded with blueprints for whatever swarms you want, bolt a nuclear battery or solar recharger to it and let it go. Hives and fabbers come with a built in 'Seymour' hive (at least that's what I'm going to call it since I had the idea 2 1/2 minutes ago) solely to keep them fed with what they need to make new hives. Hell, bolt the whole thing to a robomule with a satellite receiver and you've got every precautionists's nightmare. A mobile, theoretically controllable source of near-infinite nanoswarms. Even on its own, the thing could eventually re-sculpt an entire planet.