Also, unsure if this was already asked, but how do walkers organize and operate? Do we operate similar to modern day armor companies? Combined arms approach like today's mechanized infantry? Do we operate alongside traditional tanks and jets or are do we operate on our own?
Questions pertaining to Raptors specifically, the walker mode is incapable of flight, so when we change mid battle I assume we slow down and go close to ground before changing but how does walker to fighter work? Do the walker forms move fast enough to jump and perform short takeoffs without a dedicated runway? Or are they VTOL capable?
The exact approach of Walker warfare is mostly theoretical, since there hasn't been any large scale conflict in which to put it into practice. In theory, Walker-to-Walker conflict represents a significant portion of conflict. Infantry remaining in use for actually invading facilities or areas that Walkers cannot access, but since infantry can't pose a significant threat to an Arsenal Walker alone Walkers represent the most dominant force on the battlefield. Walkers are primarily for taking out the brunt of the opposition, with infantry for close-in or mopping up work.
Since Raptors are so new, fightercraft are still the dominant aerial force. They fulfill, in large part, the same sort of role that they do now. Whether or not they would be supplanted by Raptors is, at this point in time, largely hypothetical. Tanks are still in use, just in slightly altered capacities.
I'll freely admit, right off the bat, that this is based solely upon my relatively limited knowledge of how such things work now. As a result it's more an answer based off of how the game is run, rather than running the game based off of what the answer is.
As for Raptors, you're dead on about how they convert in battle. Getting close enough to the ground and slowing down enough to convert to humanoid. In the reverse, Raptors have significant enough thrusters even in humanoid configuration to take a running "jump", for lack of a better comparison, and convert back for take-off. Obviously that's more difficult than the reverse, but it's the present technique for going from Walker-to-fighter.