Primary care details

I am currently in the process of child mediation with my ex. We have been sharing 50/50 care until now but he has decided to move interstate to be with his gf. I will be primary carer for our 3yo.

Can people who have found themselves as primary carers shed some light on what happens now? What can I expect in the form of child support? If we choose child support, is that the entirety he would pay me? What costs should I expect him to pay for if private arrangement? Should I expect anything? Noting that I will foot extra costs just by being the primary carer, do I pay half of flight costs for father / son to see each other? Is there anything else I should know or try to prepare myself for regarding primary care? How do you cope being the primary carer? I'm glad I get more time with my son but scared about the future. I don't want to let him down.

Thank you all