We know that miners are getting reward from Bitcoin blockchain for the work they are doing for managing the blockchain.
1. I just want to know if they are already getting reward in the form of bitcoin they why there is additional fee we have to pay for every transaction?
2. bitcoin block size is 1MB. Will it remain 1MB forever or it will change its size?
Fees are not necessary for the processing of the transaction on Bloakchcain but it gives extra priority to incentivize miners for processing transactions faster in the block.
Hmm,
Question No2 is been discussed many times and it is an old-time debate some of the community stakeholder support this increase in the block size and some of them don't but in
2017 the Blocksize is already increased to the
4MB maximum (Procedure and implementation is another topic) by the introduction of the Swegwit upgrade, there are many other proposals for the increase of the Blocksize and future may be some them can be considered but they be taken in deep analysis for the reliability of the Blockchain in terms of Security and decentralization.