I see. That makes some sense.
I'm not sure I agree on the no-split - after all, if your attack is not going well, you can stop rolling and "quit while you're ahead".
There is a fairly thorough summary of all the rules (and a mention of Warlight) on the Wikipedia page:https://en.wikipedia.org/wiki/Risk_(game
It seems that, in the basic version, multi-attacks are definitely possible.
Reinforcement card values increase throughout the game. I never liked this feature (it creates ridiculous back-and-forth tides in the late game), but it's definitely a part of standard Risk play.