Photographer business registration questions

I am thinking of adding another string to my entrepreneur bow as my hobby (photography) has taken off. However, before deciding it’s useful to know what options exist for me. If I do decide to go down the photography route could you answer the following queries so that I know what is the best course of action . My photography will involve events, shoots and portraits.

1. I understand Chambre de Metier is the best MicroEntrepreneur for Photographers - if I register will it be a case of just doing the same thing as I do via my current URSAFF (liberale) job - of declaring cotisations on the same URSAFF site - or it it all done differently via the Chambre De Metier?
2. I know that Freelance MEs are unable to claim on expenses and this will be a deciding factor for me as my photography has the potential to incur large expenses (because I will need to travel and stay in hotels). Does this mean I should consider another type of business registration altogether so that I can make sure I don’t pay huge charges on hotels and travel? And if so what?
3. If I decide to ditch my other job and focus solely on photography do I need to register with any professional body or anything?

Many thanks for your help