I knew it would.
While Traya could certainly use this as an effective tactic, the element of surprise is important. In the events of KOTOR 2 the Harbinger encountered a seemingly abandoned vessel and boarded it. Not only would this not happen in the heat of battle, but it could only happen once - Revan would not make the same mistake twice. Boarding parties are the only way, and then the Republic would know they where coming and be prepared. Still, invisible assassins remain deadly whether expected or not. They lose the element of surprise though.
Good question. Like Aubere said, whether its before MSG or after it is still a nexus of dark side energy. But I'd say post-Mandalorian Wars seeing as this was the Malachor in Traya's possession. So this means a fleet battle above it would be difficult/impossible as the instable gravity would make it too dangerous. In this sense if Kreia never left Malachor, Revan would have to come and face her alone. So I advise you consider the outcome of a 1v1 fight - as it could very well come down to this. (And seeing as this is LS Revan - well as light as you can get - he would have no knowledge of Malachor, seeing as the planet begun his fall...)
And just to clarify, Meetra, Malak, Saul Karath, Nihilus and Sion are excluded from this battle. You've probably seen it already but just making sure. This rule applies to all future Kaggath threads so bear in mind if the figure is fairly prominent, most likely it will be excluded from the battle.