I think that hardiness zones are based not on the typical winter but the average "minimum" winter - which means an unusually harsh cold snap that would occur every 5-8 years or so. So it is actually very likely that something not hardy to your zone would survive after 1, 2, 3, maybe 4 or 5 years, and this would be no surprise to the folks who design the zone designations/map. But then a below-average winter comes along (but one that tends to occur periodically in the area) and wipes the whole crop out, or severely damages it. On the other hand... hardiness zones are also based on what plants need to perform as expected, not necessarily the basic minimum of survival. So planting something 2 zones below what they're marked may result in plants that thrive one year, then a bad winter hits and they get knocked back, take 2 years to recover, and then thrive again for a year before getting knocked back or reduced in numbers. So it also may be no surprise to zone map designers if your plants survive (but rarely bloom). Hardiness zones also don't work as accurately in all parts of the U.S. For example, here in CO we tend to have dry winters so sometimes something that cannot survive a zone 5 winter in Illinois or Ohio will survive a zone 5 winter here because there's no solid ice. This has especially been true for desert-type plants; penstemons in particular marked zone 6 are reliable here. Alternately, some plants might benefit from some snow cover to insulate against cold or winter dryness. My guess is with hippeastrums you WANT dry because of what was stated above about rot. So when it comes to your hippeastrums, what I would do is see if there is an area near your southern exposure that has a little roof overhang above it, which will significantly limit the precipitation there even if it's just 2 feet of overhang. Then mulch it up with some dry straw or hay every fall. I'd also amend the soil with a lot of sand/gravel and loamy stuff like peat or sawdust. My guess is hippeastrums are more cold-sensitive than cannas - not because the cells are tougher but because a canna can have 2/3 of the rhizome killed by frost and they will grow back easily in spring, whereas if you kill the top 2/3 of a hippeastrum bulb the next spring you'll just have grass. If if the ground reliably never freezes there, though, I think you're OK. One problem you might have with Christmas-blooming hippeastrums is that they just went through dormancy and expect a growing season right after they bloom. In my opinion you should keep them indoors for winter and plant them in spring. They may bloom 1 more time after planting.

Nathan, I am in North Texas, and I have about thirty brugs inground. Not Charles Grimaldi, but his parent Dr. Seuss. All have done well for me, but Dr. Seuss is exceptional. I cut them back to the ground in mid November, and mulch. They come back for me the next Spring and bloom usually beginning this month. I would see no reason why you could not successfully grow brugs inground in your climate. Hope this helps.

Not necessary to soak but should be covered. Bottom heat is helpful...germination may take three or four weeks.

I'd just to add that if you take cutting at the end of summer and put them in old brown or dark green beer bottles, with some water, they root very easily. Alternatively, if you get high enough rainfall or else don't mind watering, just stick cuttings with all the lower leaves stripped off directly into garden soil and don't allow to dry out. They should root.