Maybe it is because in Coinbase's web interface when an exchange executes, in reality, there is no interaction at all with related blockchains. the onsite exchange is just happening on Coinbase's database, while withdrawals are the ones that are really being processed on the related blockchain.
Gas prices rise based on people trying to outbid each other to make transactions faster. There is no direct tie to eth price, but it is typical to see more congestion when eth prices are higher, because there is more interest in the eth market. If congestion in the network (ie number of people trying to make transactions) is constant and people are not ...
To my knowledge swap gas fee is 21000 or so
A transfer between two EOAs (i.e. normal wallet accounts) is 21,000 gas.
As soon as you include smart contracts in the equation the gas cost increases: each opcode associated with each step in the execution of a smart contract incurs a cost. (As outlined in Appendix G of the Yellow Paper.)
Without actually digging ...
If you search this site there are multiple questions which ask the same thing but from a bit different angle, so I couldn't find an exact duplicate for your questions, although my answer has all the same data as those answers.
The transaction order in the block is entirely up to the miner to decide. And because they can decide it, they typically choose an ...
estimateGas estimates the cost of the whole transaction, not just one line of code.
For better understanding how gas cost work, I suggest you study the generated EVM bytecode and then you can even map each VM instruction to its cost by hand.
Assuming the network has the same level of congestion a transaction when ETH price is $1200 will use the same amount of Ether as the same transaction when ETH price is $1500. In your case, that means that waiting for the ETH price to dip would have no effect as you would end up with the same amount of Ether in the destination account.
In terms of the dollar ...
When you signed it, anyone (from the miners) can take it and process. With putting your signature you have made your authorization to execute the transaction. In general you have to raise gas price (10% or 15%) on transaction with the same nonce to resubmit.
There is no real queue. Mostly it's just about the gas price.
I say "mostly" because in theory the miners can include whatever transactions they wish in their blocks. But in reality they mostly include them in the order of gas price - that way they maximize their income (they get to keep the gas fees).
So it shouldn't make much difference whether ...
Ether gas fees are subjected to change based on the network usage, a simple ETH transfer based on the current gas price is about 0.0021 ETH which corresponds to 3$.
So these prices are high simply because the network usage is also high, having zero fees has the issue that you are subject to anyone spamming the network since there is no fee.
At the moment ...