Ok, got it. Now I think I understand where your confusion is coming from. All three of these links are discussing washes on the exterior of the aircraft. If you are doing something like a sludge wash (as detailed on Swanny's site), an oil wash, watercolor wash, etc. on the exterior of an aircraft it does help (or is necessary) to have a clear gloss coat down in order to remove the wash from the areas you are not intending to highlight. Panel lines are a great example. Most people can't apply a wash dead-nuts on the panel lines. Hence you need to be able to remove the excess.
If you are doing something like an oil wash, you'll be removing the excess with an "hot" thinner. In this case the gloss coat can protect the underlying paint from being removed by the thinner. Do your research though! Since you are using acrylic washes, this shouldn't be an issue.
For interior spaces as you originally discuss, meh. A clear gloss coat can help, but you'll find a lot of guys just slap the wash on the interior spaces and let it go. Primarily because it's harder to see and the additional wash can add to the shadowy effect of the interior spaces. Unless of course you happen to be using a "hot" paint or thinner that could remove the underlying paint.
Regardless if you gloss coat the interior or not, it shouldn't have any effect on your sequence of construction. For cockpits, I paint the individual pieces, assemble and then detail with washes or what have you before installing in the fuselage. I usually wash wheel wells with the rest of the exterior of the plane, which is after I've Futured and decaled the aircraft. By default the wheel wells will be Futured also, which is nice as I often clean up the wash in the wells so it doesn't look too messy.
When finished with the cockpit, install in the fuselage as directed. You can protect the finished cockpit with either the masked canopy or mask the opening in various ways. Once you finish painting the airframe, then Future the entire aircraft in prep for decaling. After decaling apply the exterior wash to highlight the panel lines as Swanny or your other references indicate.
Make sense?