I have a sunroom in the back of my house. It has a southeast exposure. Still preferable to keep outside? I do have a nice protected area for it right outside my front door.

Plants did not evolve indoors. So yeah, outdoors is preferred unless the climate is too harsh conpared to what the species is set up for

Hansen wrote:

You need to now how Google works if you want to get in to bonsai. Google would have answered your questions

1, You do not fertilize trees during winter.
2, I can recommend Biogold or any well balanced organic fertilizer with added minerals.

Good luck

I will second that.
Biogold is happiness to bonsai.