Noel,
I'll provide some quick answers to your questions - I have written more extensively about Caladium hybridization and what I've learned in articles I've posted on DG. Have you seen them?
Caladium pollen may be viable for only a day or two if kept in a small vial and refrigerated. In almost every case, I use fresh pollen. To collect it, you need to check the bloom(s) in the evening of the second day they are open. The pollen will appear on the upper part of the spadix and will look stringy. Using a small vial and an artist's paintbrush, you can collect the pollen off the spadix and place it into the vial.
As for the timing for pollinating the receiving plant, my latest knowledge is that the ideal time is the evening of first opening (the bloom opens first in the evening, not during the day). It is usually around 8 to 9 PM in the summertime. The blooms also have a fragrance at that time. If you wait until daytime, you are too late, but it is possible to have success if you pollinate a day before the bloom actually opens. I know this from experience, and until last summer, that was my standard procedure for pollinating Caladiums.
As for Caladium berries, I remove the tiny seeds from the berries and place them in distilled or RO water overnight before planting, so I don't have any problems with germination inhibitors. I do the same with Alocasia berries.
Hope this helps,
LariAnn
