Best orchid fertilizer , orchid fungus ...

[gore.m]

Hello
I have two questions :

What is the best fertilizer for orchids ?
I sometimes use slight dilution of cow-dung and special orchids fertilizer ... but I think they can grow faster

and related question :

I read somewhere orchids have some fungus on roots ... have they this fungus on roots automatically or it can be added ?
And if they have fungus on roots automatically , can fungus survive in indoor (flat) conditions ?

(I have some Phalaenopsis , Vandas , Oncidium , Epidendrum and Dendrobium)

Thanks you