The most surprising thing about it,however,is that it can land anywhere.求详解,一,however

The most surprising thing about it,however,is that it can land anywhere.求详解,一,however
前后为什么有逗号,二,is that 为什么在it前面,、三,about it是不是多写了,好像不用翻译出来.四,我觉得,The most surprising thing is that it can land anywhere.这样更好理解,为什么课文上说的如此复杂,请问这是什么语法现象,又把however写中间,又前后加标点的