I've done quite a bit of research into this topic. One of the best ways to learn about big law in Asia is by taking a look at the post by Kinney Recruiting on AbovetheLaw. They also have their own blog now at
http://www.theasiachronicles.com. They're a recruiting firm that specializes in placing big law candidates in Asia.
From what I've gathered here are the answers to your questions.
1) No, firms don't usually directly hire candidates directly from law school. Most Asian countries require you to spend X amount of years (usually 3) practicing in your home country before you can be registered as a foreign attorney. Thus, most candidates lateral over to Asia after a few years working in the U.S. Some firms might send you over if they have an in-house need. Otherwise, you'd have to use a recruiting service, like Kinney, to transfer to another firm.
2) For the most part language skills are required. There are basically four legal markets in Asia: Hong Kong, Japan, Singapore and China. Korea is still closed to foreign lawyers right now but it will open in a few years I believe [right now most of the Korean work is done in Hong Kong]. Fluency in Mandarin, Korean or Japanese is not necessarily required but definitely a huge plus. I think especially with Mandarin and Korean there are plenty of native level speakers American law schools so native level language skills are often required in the current market. That being said back when the economy was hot language skills weren't necessarily required because firms were more desperate to fill positions.
Honestly in the current economy to make the dream a reality you need to probably...
1) Go to a top law school
2) Do really well at that school [in fact 1&2 seem to be a requirement to get a big law job period these days...]
3) Get hired at a top firm [most laterals seem to be hired from top NY firms]
4) Practice in a relevant area [usually transactional work, such as M&A or project finance]
5) Have some language skills [the closer to fluent the better]
Good luck. Message me if you have further questions.