I also "inheritted" a schefflera (I am assuming this is what you mean by umbrella plant). Mine is schefflera arboricola, not variegated. The plant was severely root bound, was in the same pot for 10 years. In the spring 3 years ago, i repotted it. What i did was prune a lot of the outer roots off and teased the soil a lot to loosen up the tightly wound roots. I tried replacing as much soil as i could. I had some leaf drop afterwards, but this could also be because it was trying to become acclimated to my home. The following year i also severely pruned it because it was leggy, it responded pretty well. I plan on pruning it even further to make it more compact. I think this plant can handle a wide range of stress and responds nicely to repotting and root/trunk pruning. The plant was about 6' tall and 7' wide at first, it is now 5' tall and 4' wide, going to make it 3'x3' or 4'x4' when i prune soon.

Sorry that happened! At this point, just wait, and let it dry well before watering again. Until the pot feels much more lightweight (than it did when you brought it in from the cold, wet.)

Photos are worth a thousand words. Please, always include photos. You can battle the aphids by spraying 50/50 water with 70% isopropyl alcohol. Thoroughly spray all parts of the plant (not including the soil and roots). Was it outside in direct sun? Where is it located in the house now? How much light? how are you watering? dont use that fertilizer.

Yes it has good drainage, and wasn't overwatered. I was actually watering it with a terracotta spike and wine bottle, so if anything I think I was underwatering and heard from another forum that tropical plants prefer a deep watering and then to dry out. Someone else had said it could be salt injury due to the fact that I hadn't prewashed my top dressing of gravel, When I removed the gravel and hosed it down, it did definitely seem to be covered in a lot of some sort of residue. I flushed the plant with water to get rid of remaining salt, and am going to try some Gypsum to help it recover from the previous damage. Hope it works!