Great post. Yes, indeed, a defendant's attorney is permitted to share any information felt useful for the preparation of the case (unless the judge rules specific material to be sealed or confidential). As you might expect, the constitution requires due process and fair trials so that has been liberally interpreted to mean lawyers can and should share everything. Most courts have a local rule prohibiting a witness from sitting in to hear testimony until they have testified. This is meant to prevent a witness from tailoring what he/she says to fit prior testimony. Many courts limit this to only expert witnesses and all courts can relax or waive that rule. In any case, a defendant is ALWAYS permitted to be present (and often is required to be present in criminal cases). Most certainly both Chad and Lori will be permitted to read testimony from any case relevant to theirs.
Since we're still not to the point that murder charges are filed we don't know if the state will choose to try them together. Most likely that will be the case (see, for instance, the Dan Markel murder trial in which Magbanua and Garcia were tried together). Assuming that is the case, the most challenging aspect here for the defense attorneys is the fact that there is so much horrendous evidence against both of them independently. Defending Lori would necessarily mean choosing whether to implicitly defend Chad or to try and implicate him. Similarly, defending Chad would mean making a corollary decision. What a nightmare to be defending Lori and know that all the evidence is going to come in as to Chad's misconduct. What a nightmare to be defending Chad and knowing what a horrible mother and liar Lori is and how much of it is on record. And we haven't even discussed the added complexity of Tammy and Charles very well being additional counts against one or both of them.
If I were a capital murder qualified defense attorney I would kill to get one of these cases. I'd approach it with the idea that avoiding the death penalty would be victory and I'd handle the case with that as my primary objective. Look at how Baez rode the publicity from Casey Anthony to then represent Aaron Hernandez. He's probably got feelers out to both families now and I wouldn't be surprised to see him eventually surface after murder charges are filed.