* LaTeX is working on the iPad, see for example: http://meeting.contextgarden.net/2010/talks/2010-09-14-arthu...
* LuaTeX (http://luatex.org) is written in C, not WEB.
* You only need one binary to work with TeX. Either PDFTeX or LuaTeX. All other binaries are just glue code (for example to generate missing Metafont fonts, but who wants them these days anyway?