Yes, and with other hosting too: we choose based on your constraints and budget.
Usually two to four months depending on the features, publishing included.
We do, using developer accounts created in your name.
We check compatibility, fix if needed and republish: it is included in maintenance.
Native if Android is your main target or the hardware requires it; cross-platform to cover iOS and Android with one codebase.
When self-hosted, it stays on your server. We restrict access and encrypt the credentials used to connect to your tools.