how i can let a player type in sentences
Well, as long as you need only letters, numbers and spaces, it should be perfectly doable even without code mode at all (some symbols keys aren't working properly, though).

The largest issue would be a horrendous number of controls to be added (one control for each letter), but once you do it, you can e.g. add them all to the list, assign characters to be typed in another one and use some repeat loop to add the text to some "Sentence" attribute or something.
i can cut the sentences in words that i can use to analyze and respond
There's a block "split [ text ] into words" in Numbers & Text >> Text >> Split. It makes a list of text pieces, and you can analyze them however you wish!
Reading/writing files is another matter, but I suppose it's the limitation of Browser Flash rather than Stencyl itself (and if browser Flash actually *can* do that, I'm pretty sure you can do it in a Code Mode as well - and how would it be more difficult in Stencyl compared to Flash itself, which is a large Code Mode?); I hope that such option will arrive in Stencyl 3.0 with Windows/Mac/Linux applications export.
Also, you can use many of Flash possibilities when you use Code Mode, and I don't exactly see what Flash can do which Stencyl cannot; unless we talk about option of completely disabling Box 2D physics, whose lack actually is quite annoying and is one of the main reasons I await Stencyl 3.0 so much.
But yes, instead of doing a base from the very beginning in Flash, typing in stuff and hoping not to omit a semicolon or make a typo when writing a large chunk of code, I snap it all with some fancy blocks, sometimes enhancing the possibilities with Code Mode when needed, e.g. by making blocks for BitmapData class, which I've found extremely useful. Plus, there's a possibility of my projects working on other platforms; while I'm not sure if this'll actually happen and what that new language can do and what can't, but I hope that some basic classes would require at most rewriting a little bits of code, while the rest would be done with blocks.
who know the most are the least they share
I'm not sure if I'd count as the one to "know the most", but I'm currently working on some system which would later be applied to many more specific ones, such as, I don't know, Visual Novel Kit? Granted, that system isn't supposed to use any built-in physics at all, but as far as it's about me, I'm onto something as well. ^^'