'latin' and 'cyrillic'? I would like to be able to do that
	instantly by hotkey, as I can set up on Linux or FreeBSD -
	is there any way ?

Since the keyboard generates UTF, you'll
need to introduce some sort of translation
routine, either by hacking the kernel or by
introducing a user-level file server.

	At my work I often use telnet/ssh/ssh2 to log on different hosts
	from my desktop (now Linux or FreeBSD, sometimes with XFree86) and
	change config files with 'vi' there. Having tried plan9's 'telnet', I found
	that our hosts can support 'p9win' terminal only in dumb mode. It seems
	that reasonable 'termcap' entry for this terminal could not be
	expressed easily, so I think I need a terminal emulator like 'xterm'
	under plan9, or perhaps an ability to run x-client 'xterm' remotely and use
	local plan9 as x-server to have its window here.

Have a look at using vt before running telnet,
or even better, run u9fs or u9fs over ssh.

Russ