Spreaders and diffusers take care of that inside the cylinders.
No, it would probably lower the pump speed, to get the temp diff within 20C
Spreaders and diffusers take care of that inside the cylinders.
Your boiler is quite sophisticated. I'm pretty certain you can change the setting. It is set to operate directly on radiators, not heat a thermal store cylinder. The makers would tell you the best setting.
As it is, if 25C water is returned to the boiler from the cylinder, the boiler will only produce 45C temperature from the flow, and gradually increase the flow temp as the return temp rises. Installing a blending valve on the return between flow and return, blending water from the cylinder return and flow from the boiler, set to say 55C (condensing temp), would ensure that 75C water only ever enters the cylinder - the boiler sends hot flow water back to the return to mix with cool cylinder water to raise the return temperature.
Only having 75C water enter the top of the cylinder means that this water can be used virtually instantly, or after a minute or so, for low flow DHW purposes - a powerfull boiler mey be enough to supply one shower or more (acting as a combi heating DHW on demand). The bottom of the cylinder will eventually heat up past the 55C, and way above it. When the return temp rises above 55C, to say 58C, 78C will be entering the top of the cylinder (20C above), until either the cylinder is up to temp and/or the boiler cuts off on highest temp setting which should be 82C.