if you're after something that is automatic, i don't know how to build the hardware (and perhaps software?) you need to control the load for discharging, and the charger for recharging. so i can't offer much advice on that part.
if you're just going to manually control it, and will be there to shut off in case of problems on either charge or discharge, etc., then it's even easier, basically using high-current high-votlage contactors (like gigavac, etc) to actually pass the currents, and manual switches to engage or disengage the contactors. since this is presumably a stationary unit, size of those contactors / etc doesn't matter, so you can probably get cheaper ones as they don't have to be portable like those in an ev.
buuuut...as has already been mentioned, grin tech, makers of the cycle analyst, already have an existing project that basically does what you appear to be wanting to do, in a different way:
https://www.ebikes.ca/product-info/grinspector.html
it is a control box (that can use your existing cycle analyst) and windows software on a computer that logs (afaict) all the stuff you're after, though it doesn't presently switch as high a load as you want to. that should be easy enough to fix, by adding the contactors you'd probably be using anyway, and your load resistors, and some drive circuitry between the output of the grinspector and the contactors so that instead of the grinspector directly controlling the load resistor(s), it would control the contactors taht then control the load resistors. you'd just need to setup the load resistor bank for the proper current you expect, and then tell the software what that is. (I think--you'd want to ask grin about that part to be sure it would work).
anyway, just trying to help you simplify the project, if it is useful to you.
if not, apologies for the interruption.