To answer your questions:

Bandwidth for that many smartplugs is not an issue. Those things use next to nothing to operate.

As long as the range of the DHCP scope on your internet router (or whatever device you have assigning IP addresses) is large enough, adding 40 additional outlets/devices is no big deal. This can typically be customized on your router to whatever you want. In a typical home environment, default DHCP Scopes are set to pass out a full or half of a Class C subnet, minus a couple reserved for subnet control and 1 for the router itself. This leaves you likely 125-253 addresses usable in your home by default. Even with 60 smartplugs, this is typically more than enough. All of them "coming back up at once" is zero from a concern perspective.

Devices are assigned addresses from the DHCP Scope with a lease time. Typically multiple days. When they come back up, they should just retain the same IP info they had, so they should just start working automatically as soon as the internet router comes back up too. If power is out for multiple days (beyond lease time), the router will need to come back up first in some cases so the devices can reobtain an IP address.

If you are talking about terminating power to an outlet
These are great for control. Not for lightning/storm protection. If the machines are left plugged into the wall, even with the outlets off, or even the circuit breakers, a close-to-direct lightning strike or massive power inrush can still fry your machines... Even with the machines varistors in good working order. Shutting off the circuit breakers can prevent many in rush issues, but is not foolproof for every event that can happen. If you want totally foolproof storm protection, unplugging your machines physically is really the only option.