How to setup git repository for internal collaboration, that can be rebased easily?

Pardon if this embarrassingly simple question, I am new to git haven't found git-newbies mailing list.

We have a situation where we want to setup internal git repository that will be based on say linux-3.3 kernel.

There are about four engineers working on developing things for custom hardware. So would create a development branch say companyx-devel and we will commit all of our changes to this compnayx-devel branch.

We also want to keep upto date with latest kernel, so say if we want to move to latest 3.4-rc4 we could rebase (?) our origin to 3.4-rc4, of course fix any of the conflicts we may find etc.

We are not sure how to  go about setting up the initial import of linux3-3 kernel into git repository on of my local servers?

We know we should do following on the server:

git init --bare git config core.sharedrepository 1

Should we be cloning the linux kernel on the server? git clone path-to-kernel-org-git-tree

Or I should clone the tree from kernel.dot.org client and then push it to my local git repo?

We tried cloning the tree from kernel.dot.org on client and pushing it to our internal server but that doesn't push kernel code as cloned directory already has .git directory.

Is there a document/web page one can refer to that might help us handling this scenario?

-Kumar