As for the titan speed it has to be somewhat slow, if they go too fast people with high ping can warp through walls, this happened in the lambda class shuttle and the falcon on GC if you walked on board without actually "entering" it. but if the collision is still the same as it was on BF2 the passengers could die if they run too fast into the wall of a titan while making their way aft.

there is one other way of course.. that the interior of the titan is "portalled" like ut and other engines use.. so its basically static.. but the exterior moves.

So does this imply that DiCE has changed engine to allow players to be on vehicles without being in it?

I for one hope so. If this is possible then the team might be able to have interiors for corvettes, just keep them slow.