Regarding learning AGS, take these words to heart: if you're not prepared to do all you have to do to learn and program as much as possible, quit now. Game developing (even for a remake, or in this case "demake") is no walk in the park. I've started numerous game projects and all of them fell by the wayside because I just lost interest or other stuff came up. I started with no experience but gradually learned until being a fairly experienced programmer. Don't look for the "easiest" way to do it or the final product won't be any good. Not because of the game engine you're using, but because you're already in the mindest of shirking as much work as you have to to get it done and the final product will suffer.
Generally speaking AGS is the way to go if you want to make a LucasArts-like adventure game. That's just all there is to it. It WILL work for you. You should just suck it up and plow ahead or give up now. Hard words I know, but it'll save you heartache and self-pity later when you give up and it never sees release, or it does get completed and everyone says it sucks because you didn't put enough work in.
To sum up: there is no "easy way" to make a good adventure game. You have to be willing to put everything into it or the outcome will suffer.
"Booyah! Look out, LeChuck! Here comes Guybrush Threepwood's glowing sword of hot monkey vengeance!"
-Guybrush Threepwood, Tales of Monkey Island