A lot of those questions have variable answers and I would advise you to research thoroughly before deciding the route you'd like to take. As a bit of an overview:
NFT's are available on lots of different blockchains, from Hive, to Ethereum, to Wax, Solana, and many many more. Unless you are planning to build your own blockchain you will need to decide which chain to build on.
The cost for creation and distribution of NFT's is going to depend entirely on which chain you choose to deploy on and which marketplaces you are planning to sell them in. As an example the cost to "mint" an NFT on Hive is small in comparison to the cost to mint on Ethereum but the market is much larger on Ethereum so the potential to earn is much higher as well.
Many developers choose to deploy their own marketplace where the NFTs can be bought initially, and then buyers are able to take that NFT be sold on secondary markets like opensea etc.
If you are an artist wishing to avoid development work- you could just tokenize your artwork on an existing platform like Opensea on Ethereum or NFTShowroom here on Hive and then market your work to bring in buyers.
There are many many different options available for NFT creation and distribution out there and this really doesn't cover much at all!
Good luck and I hope to see some of your work soon!