Well, there are a couple options. First, you can just go to Google.com and search the word you're looking for. The first search result that comes up should say something like "Merriam-Webster Online Definition for ______" and click on that. That should give you the definition of the word.
The second option you have is to go to an online dictionary and just type the word you want to know the meaning of in the search bar. I use dictionary.com or merriam-webster.com, but any one works. Just type the word in the search bar at the top of the page and then you're golden!
To spell, and to find meanings
yes! of course
I think you could make the argument that the word "pointless", by definition, is the most pointless word in the English Dictionary.
No, it is not. If you look it up in the dictionary you will see it is a childish word that people make up. But if you look on the SCRABBLE dictionary on Pogo.com it is but they made it up.
Good morning and good night are two separate words.