Reference doubts

[Enrico Colombini <erix@...>]

I am working on a Lua reference card (much more work than I thought...) and 
I'd like a few clarifications w/rt the reference manual + the Book:

1) Metatables are described as part of the language core, but getmetatable() 
and setmetatable() are part of the basic library. What can one do with 
metatables without the basic library? Use them from the C side only?

2) The reference guide lists xpcall() as having 2 args only; does it accept 
user's args after those, like pcall(), I presume?

3) Is the "byte counter" quoted for collectgarbage() the same as the "dynamic 
memory that Lua is using" returned by gcinfo()?

4) gcinfo() and collectgarbage() memory amounts are expressed in "Kbytes". For 
the sake of SI-correctness :-) must they be interpreted as kB (1000 bytes) or 
as KiB (1024 bytes)?

  Enrico