Hello,
My name is Saya and I am a freelance translator / PR representative strategist.
I am currently working on something similar with a client in Tokyo, to manage their facebook / twitter / website and tumblr in English and Japanese.
I'd first set up a monthly posting schedule for my client. All the posts for each SNS would be drafted on google doc and will be posted accordingly to the schedule upon approval from the client. All images and videos are edited by my client, but I will be able to edit image re-size on my own (not sure i can edit videos.)
My proposing rate for your project is 500 USD per month for now. If you are interested, please reach me via chat to discuss further. I am happy to share the results and progress of social media engagement for my Japanese clients.
Thanks for your time in advance.
Saya