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Actually creating a BSC token is very easy, even much easier than creating an Ethereum token. We just need to do Ethereum code combination for BSC. But you can also do it automatically via DexTool.
Registering an ICO is like promoting your token to investors publicly. You can do this without the involvement of the exchange, in contrast to you registering for an IEO, of course it requires the involvement of the exchange, but the success rate is much higher than with an ICO.
As for the cost, if you generate tokens manually, the costs are much lower than creating tokens in DexTool. You can check it in DexTool.
To register on the exchange of course you must meet the requirements given by the exchange. You must have an official website, telegram group and many others. You also need to pay a lot of money to register on the exchange, unless you can pass the voting process.
BSC or any other chain would be good too I guess, it's easier to go with that than to develop a new coin! I think OP is not serious with this, if he is serious he would do his own research and he would come up with some other more complex questions. He could check google for the answers to these basic questions and he would find many answers and articles about this matter... if he spent a bit more time listing this forum he would find answers as well... so if he didn't make that little effort why should we believe that he is ready to start something serious like creating a functional alt?!