Hey,
Thanks for posting project for odoo,
I am Raj, Odoo consultant.
1) hosting offer lowest cost : best option is AWS, also as initial level/testing purpose providing free tier for 1 year. without any cost. and its seems good for 3-4 users.
2) Install/setup odoo : Yeah that I can do for you and 9.0 community is best suite as per given requirements.
3) Will provide full functional training and setup proper e-com flow with payment gateways integration
4) Also we integrate ebay with e-com store.
I request you to open a line of communication and share more detail of this project. So based on that we can discuss the depth of the project requirement and move ahead quickly.
Feel free to share NDA, if you need to sign with us before sharing the further detail.
Thanks,
Raj
Caret @ Team