a.)
To use several Asian Glyphs one has to register additional Fonts in the JDK 1.5 fontconfig.properties file (here as an example the fontconfig.RedHat.properties.src file from build 51a):

# Font File Names

filename.-arphic_technology_co.-ar_pl_mingti2l_big5-medium-r-normal--*-%d-*-*-c-*-iso10646-1=/usr/share/fonts/zh_TW/TrueType
/bsmi00lp.ttf
filename.-misc-baekmuk_batang-medium-r-normal--*-%d-*-*-c-*-iso10646-1=/usr/share/fonts/ko/TrueType/batang.ttf
filename.-misc-baekmuk_gulim-medium-r-normal--*-%d-*-*-c-*-iso10646-1=/usr/share/fonts/ko/TrueType/gulim.ttf
filename.-misc-kochi_gothic-medium-r-normal--*-%d-*-*-c-*-jisx0208.1983-0=/usr/share/fonts/ja/TrueType/kochi-gothic.ttf
filename.-misc-kochi_mincho-medium-r-normal--*-%d-*-*-c-*-jisx0208.1983-0=/usr/share/fonts/ja/TrueType/kochi-mincho.ttf
filename.-misc-zysong18030-medium-r-normal--*-%d-*-*-c-*-iso10646-1=/usr/share/fonts/zh_CN/TrueType/zysong.ttf

In addition, you have to register X11 fontpaths to java in the following section:

# AWT X11 font paths
awtfontpath.latin-1=/usr/X11R6/lib/X11/fonts/Type1
awtfontpath.chinese-big5=/usr/share/fonts/zh_TW/TrueType
awtfontpath.chinese-gb18030=/usr/share/fonts/zh_CN/TrueType
awtfontpath.japanese-x0208=/usr/share/fonts/ja/TrueType
awtfontpath.korean=/usr/share/fonts/ko/TrueType

Because the filepaths are absolute, this scheme will break except in the rare cases of a home user's out-of-the-box Linux Installation with a popular Distribution ( See 5014112, 4890369 for examples).

The majority of business installations use fontservers, remote-boot with shared font directories or imaged installations with modified font locations. Common to all these installations is a non-default location of the fonts. The Tiger Documentation for Font Configuration states, that by modifying the fontconfig.properties file, the customer will loose his support for these installation. The customer will end up in the deadlock of an JDK supplied configuration which will not work, but cannot change without loosing support.

To our believe, this aproach is fundamentally flawed. You force yourself to qualify supported and unsupported Linux-Distros, which you will see seldom in the field and if you find them, you need to play cath-up with the actual locations of fonts in that distribution.

b.)
The fonts used for a given writing system on a given platform are not documented.
So it is not known which fonts have to be installed to get a fully functional system.