1) Why do you say I'm writing to you to find out about hotel accommodation BUT
I'm e-mailing you to find out ...
thank you
I'm passionate about photography is that same as I'm fond of photography?
I don't know why some verbs take an indirect object (I'm emailing you...) and some don't (I'm writing to you). There are some usage things in every language that just aren't explainable!!
The word "passionate" is much stronger than "fond". Someone who is passionate about something would give up other activities to pursue his/her passion. Being fond of something is a much milder term.