JGit vs. Git

Hi,

I am a git and a jgit noob. Be gentle. :-)

1) Is JGit a drop in replacement of Git? In sense, if I were to pack
in an SCM with my app, Can I pack jgit instead of C Git?

2) I noticed that there are no 'add' and 'commit' commands (at least
from the source) in the org.spearce.git.pgm project. I am looking at
the repo.or.cz/egit.git repo. I had a brief look at the
lib/GitIndex.java and lib/Repository.java. GitIndex has the add
methods to add files/entries to the index. I am still stumped on how
commits can be done with JGit. Any help is hugely appreciated.

I am working on Windows with msysGit behind a HTTP Proxy. (Life cant get worse, I guess.) . I planned on using grit via JRuby but grit uses fork which is not available on funny platforms like windows. And JRuby guys do not have any plan on supporting fork even on platforms on which for is supported. If JGit is a pure Java based implementation of Git with more or less the same functionality, then my work becomes a lot easier.

Regards, Vagmi