Do bonsai kept indoors go through same dormant period as those kept outside, even though they are not subject to the temperature differentials? Can we fertilize all year?
No they don't go through a dormancy period, that's why you have to bring them inside. Tropicals and other "indoor" trees can grow all year (under the right conditions) so you can fertilize all year as well. Just be sure to provide enough light, if you don't have a large sunny window then you may need an artificial grow light
Do bonsai kept indoors go through same dormant period as those kept outside, even though they are not subject to the temperature differentials? Can we fertilize all year?
Depends on the species of tree. Some trees you CAN'T keep indoors. Some trees you can keep indoors, but they will mimic their outdoor growing behavior. True tropicals can be kept indoors, and (assuming you meet all their care requirements) they will continue to grow year-round.
Since the title of your thread was "dwarf jade" I'll assume you are talking about succulents. My succulents continue to grow year-round... even when outdoors by my other trees that are going dormant and dropping leaves.