Nah, I'm old school, learned English to play video games, mostly old RPGs, but I'm inclined to learn Japanese just to get some new games (and videos, of course).
VNs maybe are good fr you to be immerged in the language, getting used to some constructions and phrases, but please try to have traditional classes to proper learn the language.
More like I learned english THROUGH adult games in general
Never been a fan of VNs, took me a while to play and actually enjoy it, but in the beginning RPGM used to be my favorite type of games, and nowadays it's sandbox (usually through Ren'Py/Unity)
No. I learned English thanks to videogames on NES. On PlayStation I learned how to pronounce words right. I've learned English in school as well, but my classmates wasn't into leaning English during those classes and often cause problem to those pupils who wanted to study.