RCA,
I don't feel I am knowledged enough to answer most of your questions, but I can offer my thoughts for a few of your questions; my replies are in regards to silver. I have no experience and have not read up on gold.
First off, in regards to what quality of coins. It depends on why you are buying the coins.
If you are buying for financial
investment, then go with the shiny pretty stuff. I may be off base on the following, so someone please chime in if I am mistaken: numismatic/collector quality coins will generally be individually wrapped/packaged with a quality rating on the package such as pf, ms, au, ef, vf, vg, g, or ag. They will also have a number following.
If you are buying for financial
meltdown reasons, I'd go with 90% (also called junk silver). The reasons are as follows: there is no reason to pay a premium for coins you will be using for trade. You should be able to get 90% coins for real close to the spot price. Why pay an extra dollar or more over spot for a silver eagle? The next reason I like 90% is because of the variety of amounts of silver between the dimes, quarters, halves, and dollars. It simply gives more versatility. Why deal with trading for something worth $5 with a coin worth $20 and hoping the person you are trading with has proper change?
If you are getting these coins for financial meltdown reasons, personally, I'd stick with coins minted/used in the country you plan to trade them in. Collectors and dealers may know what a foreign minted coin is, but I feel safer in the fact that U.S. minted coins will be more recognizable in the U.S. by the average Joe, such as the baker, doctor, or whoever may be getting these from you in a trade situation.
As for what combination, that would depend on your preferences as well as amount of $$$ you can spend and in what time frame. Personally, I can't lay out a lot of money, so I would buy 90% monthly and as my supply gets larger, I would start buying a bit of gold to go with my additional purchases of 90%. Keep in mind, the smallest currently minted U.S. gold coin is 1/10th oz. This equates to about $98 dollars today. So whatever combination you decide to get, be aware that a coin worth $98 is gonna suck to get change for a loaf of bread. So what I am suggesting is that you get the majority of your coins in lesser valued coins. Of course some of the larger valued coins will be of use if you need a tooth pulled, need a major piece of equipment, etc.
As for storage: some people rubber cement coins to the underside of tables, bed frames, entertainment centers, etc. You can also used the old standbyes such as the hollowed out book, the fake hairspray can, and things like that. You can bury them in an airtight/waterproof container. For safes, don't get something that can be carried off like the ones at the box stores for $50. Look at a good firearm safe or a safe safe like my father has... about 3'x3' safe that weighs a ton. It was my grand fathers... made when they made good stuff.
Just some thoughts from my non-PHd knowledge
