delaflaquita I put in "http://localhost:50000/" and it didn't work. It says, "Server not available".
You need to enable the preview over wifi inside C2
matrixreal it is not as easy as that, cocoonJS and Ejecta are actually engines, they are just not based off nor working like browsers engines, and so they lack some features (notably every form control, but not only), also while ejecta is open source , cocoonjs is maintained by ludei, and they have troubles so their focus is not what it should be (I think they are trying to have an investor so they can get up again, but it does not seem to bode well for them).
Crosswalk is chrome for android combined with you game, as an apk with some API access (so based on an open source browser engine, an maintained by companies with a assured future before them), phonegap is basically just the game communicating with the webview of the device and the APIs (basically it runs on the integrated browser engine on all android and iOS devices, however it is not that great until android L and iOS8).
Also all of them supports canvas2D, to be exact, if webGL is not possible, canvas2D will be used as a fallback
Webgl tends to be faster, except in some particular cases, so it is recommended to let it on, but you can set it off inside C2 if you ever need it.