1. One night, we had an overnight temperature of 52 degrees. This seems
too cold to me, and seems like a clue to bring in the orchids real soon.

As far as the temps go, just watch that it isn't going much under 50 for
extended periods. In fact, your Phals are probably enjoying the diurnal
range, since they need a bit of chill to encourage spiking later in fall.
The oncidiums, in my experience, anyway, will throw a hissy fit if they get
too cold.

2. An oncidium looks like it has a problem with a bacterial/virus type
infection, and I need to spray it with funginex. A couple of the phals have
scale and what appears to be a bacterial infection (pitted leaves that look
like those that were recently posted). I read (somewhere) that one shouldn't
dose an orchid with both a pesticide and fungicide at the same time. Ok, if
I want to use both treatments, how long should I wait between the two
treatments? Until one dries? A day? A week?

If you use a natural insecticide on the scale (here's a link for you:
www.firstrays.com then go to the page on natural remedies), then I don't
see why you couldn't go ahead and use your chemicals the next day. Both the
scale and the infections that you reference can do a lot of damage fast, so
the sooner the better.

Diana