> I was always scratching my head over why this place needs a period and that place doesn’t

I like Fred Hebert's (author of http://learnyousomeerlang.com/) explanation of syntax on his blog:

http://ferd.ca/on-erlang-s-syntax.html

At least the "template" explanation is most helpful to me.

> then there was just plain weird stuff like one-based indexes.

Interestingly, I don't think indexing is really that common in idiomatic Erlang. In other words when processing lists, one can split them into head and tail [H|T] or uses folds and maps.