A miner has the ability to choose the transaction ordering for the block they are attempting to mine however they want. (The only constraint I can think of is that if one address has multiple transactions submitted, the miner must order lower nonces first.) This has a number of interesting ramifications - Flashbots, for example, can (and do) request from ...
Minor blockchain reorganisations up to 6 blocks deep are normal for Ethereum. Ethereum mainnet with proof of work has only probabilistic finality, not true finality and any block is subject to disappearing.
More about finality here.
in order to be on top of the big transaction, the front-runner would use more gas allocation than that big transaction. if you add even 1 wei over a trx you would be able to jump on top of it in the block index count.
so that's how it is done.
Just for info, there are multiple ways being implemented to circumvent front running transactions like personalized ...
I don't think it is possible, the transaction index is a computed value after the block is mined. the index is determined by how much gas you are paying for the transaction.
To be on the top you pay more but to be in the middle you need to pay more than the transaction lower than you and less than the one on top of you. the price you are paying is the ...
There is no written rule on this, miners and full nodes can set themselves what kind of block timestamp skew they tolerate.
In practice, there has not been any notable timestamp skew ever. The block time itself is ~15 seconds (I guess that where the misconception raises), so my rule of thumb is it would be accurate to a minute.