A.J. Woo wrote:

1)  who's Ironfist Chinmi?

He's the main character of Ironfist Chinmi, created by Takeshi Maekawa.
The manga is being published and translated by Bloomsbury Children's
Books (which, I may say; has done a very good job. All the Japanese
'sound effects' have been retained).

The manga first appeared in 18th November by Kodansha, Tokyo. Btw, the
translation of the manga is being done in Great Britain (up to volume 14
now), so it's no surprise if no one has heard of it yet... 

Set in China (nearing he Opium War, but no date was given), Chinmi is an
orphaned boy living with his elder sister. He caught the attention of a
wandering kung-fu teacher who took him into Shaolin Temple. In the
course of his adventures (so far), he has learnt the various styles of
Chinese Kung Fu (Pointed Fist, Chi Manipulation, Zen...) and helped a
lot of people in his way. He also has a pet monkey, Gokuwa. The manga
(I'm not sure if there is an anime series) is a light-hearted one,
action-packed but with moments of humour as well.

Here's what the publishers say:
"It was predicted that a youth would come to the Dailin Temple. He would
have a Fist of Iron, Legs of Stone and Clarity of Thought and Vision.
With his natural intelligence and extraordinary skills in the ancient
Chinese martial art of unarmed combat, the fearless boy-hero Chinmi
could be the long-awaited 'Magic Fist'."

2)  power difference might have something to do with the tone of the
series.  Remember, Ranma 1/2's a comedy, none of the characters have the
earmarks of great villans

To tell the truth.. I've NEVER seen Ranma 1/2 before. Yet I have read
fanfics and information from the net to know and enjoy Ranma. From what
I know, Ranma doesn't seem to have arch villians like Batman, but so
does Chinmi. In fact, Chinmi doesn't even has someone like Ryoga. He
does have two girls liking him however...

Ironfist Chinmi doesn't sound like a comedy and so his opponents are
probably more dangerous/serious/etc.

The latter part is true, his opponents are serious and deadly. Imagine a
killer with a poisoned hand, a bandit whose palm strikes can mush
watermellons inside without breaking the skin, an American (?) boxer...
His various teachers range from a temple abbot, warrior, blind
staff-master... even a GrandMaster of Dirty Tricks!

-- 
'Raging Demon' Arion Wong