> dealing with radiation
I can at least answer this part of the question. (I have had NASA contracts working on radiation tech, though not in that sector currently)
You can use COTS. Just depends how reliable you want it. There's a good interview on EEV blog with one of the XPrize contestants. [0] He talks in detail about how they handle radiation (they basically don't and hope for the best).
If you have a mission critical design or are sending to a more extreme environment, like Mars, then you actually have to deal with radiation. Commonly this is done with rad hard chips. Instead of silicon they use sapphire. Sapphire is what is considered rad hard. Downside is that these chips tend to be older and not nearly as powerful as current technology. They will also encase more vital parts in tungsten (especially see Jovian probe designs). Good news is that there's lots of work being done to determine how to make COTS viable (also a LOT cheaper). There's plenty of NASA SBIR/STTR topics on the subject if you want to try your hand at it AND get paid! Note: many abstracts for proposals are public, so you can see what others are attempting.
As for LEO and MEO, again it depends on how mission critical you are. Companies like Planet Labs (LEO) don't really concern themselves with radiation (most cube sats don't). They will just reprogram their satellites or take the hit. Typically GEO satellites are very rad hard, because the nature of the mission is to be there a long time and it is extremely expensive to get into that orbit. Typically they go with the tungsten box and rad hard chip design.
On the ISS they do a fair amount of research testing shielding. But they are also concerned with debris. So while you may know about aluminum other materials that are good also include Kevlar and Spectra (Ultra High Molecular Weight PE: which is used in grocery bags). People are experimenting with doping these materials, interweaving, different layering conditions, and all sorts of things. Pretty fascinating (and frustrating) work. Hydrogens help get rid of neutrons but you need dense materials for neutrons AND everything else. Note: ISS is in LEO and though you'd get lethal dosages on extended stays with no shielding, rad levels are fairly low.
Btw, lots of this work can be done with only some basic understanding of particle physics and can be tested with open source tools like GEANT4[1]! (there are better non-open source tools) Since it is one of these extremely large solution spaces, who knows, you might get lucky! You can play around with different low density materials (like plastics) and high density materials or metals. Goal is light, cheap, and effective.
[0] https://www.youtube.com/watch?v=nJLOZDPTp3I (3? episodes. There's a few)
[1] http://geant4.web.cern.ch/ (this is difficult. I do have some tutorials if anyone is interested)
P.S. I can also talk about some of the other stuff, but in less detail since it wasn't my focus. But figured this was long winded enough. Let me know if there is more interest.