Pose estimation in unknown scene

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All I have is the internal parameters. Is the scale of T related in any way with focal length? I mean, the essential matrix is found with the help of the internal camera matrix. I was wondering if T and the focal length could be related. Another question: If I have multiple images taken with the same camera, and find the pose between pairs, would the translation between such pairs be proportional? i.e.: would all the pairwise translations be in the same "unit"?

For your first question, no. The essential matrix itself is up to scale. What you're getting is the epipolar geometry of the scene, which basically describes the relationship of the two cameras to points in the scene. It's all projective though, so all you'll get from the scene is the geometry, but no scale. You can read more on its properties here, but a quick summary is that the essential matrix multiplied by any scale will give you the same generalized scene geometry.

For your second question, when you start introducing more cameras, rather than calculating a matrix for each pair, you'll calculate a single matrix that describes the scene geometry between all of them them. For example, with 3 separate poses/cameras, you can calculate the "Trifocal tensor" (The fundamental matrix is a bifocal tensor). Having N-cameras, and you can calculate the "N-Focal tensor." It will describe the geometry between the cameras, but again, only up to a scale. Without external information, you won't get scale. For a whole book on these matrices, read Multiple View Geometry by Hartley and Zisserman. It's practically the bible on this subject.