This is the conversations page... I only look here to see if there is a spark of life. You will get much more response if you post your question over on Orchid Discussions.
I think you have a Phalaenopsis Orchid and its growing out of its pot is a good sign. The reason not to put it into a larger pot is more to do with possible overwatering than filling the pot with roots.
You do not need special orchid fertiliser, orchids are plants so whatever you use on your indoor/outdoor plants might suffice...
Anyway, repost over on discussions, maybe the answers to some of your questions are there in the current or past threads, also google Phalaenopsis and look at the images to see if i have guessed right re. the type of your orchid.