USB mains sockets opinion

Indeed.

I'd say the limit will be set by existing USB connectors.

One would hope that a lithium battery installed in a device would have the appropriate charge limiting and regulation circuitry within the device.

Supplying a USB device from a power source capable of sourcing say 100A at 5v should *never* cause any issues.

as far as I've been told (by engineers current in the practise of Li-Ion technology) all Li-Ion battery packs *must* contain local safety and regulator electronics:

I assumed (and this point alone may be wrong) that the safety circuit would prevent overcharging and over-fast charging? Anyone know any better?

It has some protection within the battery pack itself.

some cells do, others don't

Not too fussed about which way up, but I'd like a good multi port charger - have a fairly cheap two port and it works even on my (old) iPad. But would like the convenience of three/four ports and all able to supply full power.

Also looking for a similar spec. but for a car lighter socket... Several out there but am finding it difficult to assess quality from the screen.