Two parts to this response, solicited and unsolicited:
Without knowing what version you're using, selecting all the layers you want
to change in the dialog at once will allow you to change all their colors to
a single color in one go. You have to select the color box next to one of
the selected layers to change them all, and hit OK. If you want to change
them to various colors you will have to do that one (or a few) at a time.
XREFing for plans for a house would seem to me to be a cumbersome,
inefficient system. If your layering system for various floors uses the same
layer names (also not something I would do) I can see that XREFing would
allow you to refer to other plans in each plan. However, with processor
speed being what it is, and the drawing process being kind of circular at
times, I find that having the entire model (all layers) easily editable in
the same file to be the way to go in smallish buildings, especially in
houses. In my protocol the layers related to various plans (and other views)
are logically grouped by a prefix. They can be turned off or on quickly as
needed by using wildcards, you can copy from one plan to another easily, and
you never have to fuss around with XREFs.
If you go to my CAD page, the background is what a house dwg file looks like
with everything turned on. Layer management can be automated in a number of
ways (I use toolbars). Further the elevations are spread around the plan to
make their coordination easier, so if you make a plan change that affects
the elevation, you can make the elevation change immediately and correctly.
The building sections are 'layered' over the elevations for the same reason
the plans are 'layered' on top of each other. Of course, it means you have
to use paperspace to plot.
I've done a lot of houses and small buildings since r 12 in '95 and think it
faster and much easier to coordinate. I have also developed a bunch of lisp
routines related to this way of working which are on my site. If you like
I'll send you a file to examine. The usual initial reaction is "man that's
complicated!" but after a bit the advantages begin to become apparent.
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