I think you have to ask yourself, how much do you want. If you are content with the basics, temperature, humidity,wind, then the Vantage Vue is for you.
If you want to know ET, THSW, solar and uv and maybe sensors in other locations, then the VP2 plus is for you, clearly more money invested.
To get to the internet, then you need a datalogger, both use the same type, either serial, usb or IP depends on your computer or router. and OS. There are PC and MAC versions
Software, I prefer Weatherdisplay, a little trickier to use, but most bang for the buck.. try the trial version , you won't be unhappy.
You can use the Weatherlink that comes with the Davis logger (all have the same software) , VWS, Cumulus, you have to see what is available, trial version and make a decision.