Hello,
I will start with the number 3 question:
The caskets that you can open in the temple, can offer something (resources, army, decrease in construction time or happines) or they can be empty (only one guaranteed to NOT be empty is the EXTRA+ option on diamonds). It's like a game of luck if you will. However when they do offer something (in resources or army units) the number from where they start is 1. So they can offer 1 army unit or 1 wood (for example) OR according to the following descrition from here
http://tinyurl.com/pmlyw8d.
2. Hidden colonies are not really hidden. They are for example very smartly placed in the top corner of a map in a forest terrain type, making it pretty hard to visualize. But its there. If you look closely you`ll see it.
1. As per the market, the offers do appear in the market. But let me give you an example, when I click to buy 2000000 wood, I open the market (I see the price there) I type the amount of the resource (or just click the available gold and buy for all I got) and IF when I click buy, another offer had just been posted even for a fraction of a second, I will get that amount also. The warning message about the price being changed only shows up if the price went up. If you are talking about other offers, then I would need a proof of the existence of those resources on that market..
Also the market doesnt allow you to put an offer two times higher then the highest offer existent in the market, however it has no coefficient regarding how low a price can be. You can set your offer starting with 0.1 per unit. And if you are fast enough to get it, then you got it. This may be a common practice within an alliance, if a colleague asks for help to get iron lets say.. alliance members may jump to his aid with offers lower then on the market and that person asking for help will be watching the market for it..
Hope this helps.