I know Mormonism has its own, well, quirks, but at its basis is the same Christianity other denominations practice. Even if they don't do the whole Lent thing, you'd think they'd know about one of the basic holy days in the Christian liturgy.
Not really. I grew up in the Methodist and Presbyterian churches and no church I attended
ever did the ashes. It wasn't until a few years ago that I noticed protestant denominations participating in the practice. Personally, I couldn't care less. It's not a scriptural requirement, just a tradition or custom, but if it draws people to repentance and thoughtfulness about what the crucifixion means, great.
It's not accurate to say LDS is "the same Christianity" as denominations like Methodist, Baptist, and Presbyterian, however. What you call quirks are part of what distinguishes it from orthodox (small o) Christianity.
No, I'm not proposing a big discussion on religion here, because I know Myst does not want that for the forum. So I'll say no more.