Questions about DIR

How does one go about obtaining DIR style equipment? Halcyon makes BCs
and lights, and much of the remainder is just buying certain types of
items (e.g. ScubaPro Jet Fins), but what about regulators? Do they have
to be custom made to get the right hose lengths?

Also, the GUE web site says...
"The second stage NEEDS to be able to be stripped under water, just in
case there is debris under the exhaust valve or it has moved (i.e.
folded back) causing the second stage to breathe wet. As such, the face
plate needs to be removable without any tools, while wearing gloves."

Are most regulators capable of being field stripped under water? How
would you know? I've been looking around on the web for information on
regulators lately and haven't found much real information. Most of what
I have found is simply marketing hype.