For most regular coins the premine amount/blockreward structure can bee seen through github/src/main.cpp and searching for the word "nsubsidy".

For example:

https://github.com/PIVX-Project/PIVX/blob/master/src/main.cpp#L1617

nHeight is the block number and subsidy is the blockreward.

So if you see this:

    if (nHeight == 0) {
        nSubsidy = 60001 * COIN;

That means that there's a 60001 premine at block 1 (0).

You can check on the pool.

well price of bitcoin is not that different from price of anything else. it is being determined based on supply and demand.
if someone has already explained it to you i really can't put it in any other words to make it better.
but maybe these links can help more: http://www.investopedia.com/university/economics/economics3.asp
https://en.wikipedia.org/wiki/Supply_and_demand

usually for supply and demand i see people use the example of winter cloths. in summer time nobody buys winter clothing so the demand goes down and you may find them under their real price. and in winter everyone wants to buy them so the demand goes up and as a result the prices can go higher too.

No.
being centralized or not has nothing to do with the price. the centralized government doesn't set the price of everything. and even if they do they still do it based on supply and demand.

for example in the winter clothes example, there is no centralized authority setting the price of a winter hat for example. the shops or the business owners decide that this year they can sell hats at $X higher than last year based on weather being colder and the demand being higher

no it is how the market will work. the exchanges don't sell bitcoin, the exchanges are just platforms that allow people selling and buying bitcoin to meet each other. and if people on one exchange decide to sell their coins the price goes lower and if they decide to buy more than other places the price goes higher. and if the difference becomes big enough to become profitable then people from other places will come to the exchange with different price and make trades in a way to balance things out.

for example if the price is lower on bitstamp like be $2000 people can go there and buy cheap coins until it comes back up to $2500 like other exchanges.
or if it is higher like $3000 they can go there and sell their coins until it comes down to $2500 like other places.

but it usually doesn't come to that point. if price goes to $2400 for example there will be more incentive by the same people on bitstamp to buy more until it comes up. or the same if it goes to $2600
the difference that you sometimes see is because some exchanges have trouble with deposits or withdrawals or have higher fees that leads to that incentive to trade there to be less.

True, my question is for efficient markets (rather exchanges), whenever they'll be, where there is limited or no scope of arbitrage.

there is a button at the bottom left side of the page called "move topic"

How many coins premined?
Already mined 34k blocks?