Container ships typically can sail between 16-25 knots, though they most often sail in the lower-end/lower-half range of speeds for fuel efficiency (if not even lower in some cases).
There are also fast container ships that can sail very fast, such as the Mearsk B-class ships with ~4200 TEUs that can cruise at 29 knots and at speed of up to 37 knots. However, they are more expensive to operate, and they are only available in significantly low numbers.
For the larger, transoceanic boxships, that is correct.
100 TEU boat like the one pictured here are however coastal/riverine cargo vessels. They operate at about 10-15 knots. No point making them any faster given that the bulk of time is spent loading/unloading and increased speed of transit won't lead to significant time savings given the distances involved and/or proportion of time spent in transit.
Such armed container ships can also loiter and/or outright be stationary in the middle of the Bohai, Yellow, East and South China Seas. They could serve as forward pickets + SAM batteries that would extend China's SAM coverage into the sea from the Chinese shorelines, alongside serving as backup SAM batteries for the Chinese-held islands/atolls in the SCS.
Yeah, pretty much this.
Especially if you think in terms of a Taiwan scenario. Ground based AD rings from Mainland China won't reach over the Taiwan - making any coverage of the Taiwan island largely from land-based air or sea borne platforms.
Putting small box ships out in the middle of the straits takes a big load off the air and naval platforms, as long as the missiles themselves are capable of CEC and take targeting data from other platforms. This makes for a very cheap platform (these 100 TEU ships go for about $1m bare) akin to the ground based launchers themselves.
So yes, being able to take a 100-teu containerships and add a Type-052B Frigate-level sensor suite, combat management system and CEC would be very useful. You could quickly add a large number of Frigates.
If you use a larger container ship with more VLS cells, then it becomes an arsenal ship of sorts.
That would leave Chinese shipyards able to focus on higher-end warships (Destroyer-level and above)
Not quite sure about the need to put a radar on it, let alone an either frigate level sensor suite and CMS really. That just increases the cost of the platform significantly and more importantly the exposure of valuable trained crew (tech and command) on loss of a less-than-ideal platform.
Makes more sense to have this as a cheap-dumb arsenal ship to move range rings within heavily defended bastions than to have a fully capable, self-defending ship able to operate as a picket, at which point, you're better off just using a full frigate. Hull is cheap. Sensors and Crew ain't.
2. There are 2 life rafts between the decoy launchers so it’s probably lightly manned.
There's also the original life boats on davits next to the bridge, suggesting that either this is either redundancy given the likelihood of non-civil damage or extra crewing over and above the normal crew levels of such a boat.
