Charging wattage
My default charger is a 96W charger which is a fast charger. Fast charging as we know is not good for the battery. I have tried with a 35W charger, but that is not sufficiently high enough to charge the battery and run the machine.
You cannot manage the amount of current flowing from the charger; this is not how this works. First, current is drawn, not pushed. The device (MacBook, iPad, iPhone, etc.) negotiates with with the charger to deliver what it’s asking for. Secondly, the wattage rating on the charger is the maximum current output, not what it delivers all the time. Your 96W charger could be outputting just 3 watts at any time.
Charging to 70/80%
There is no need to do this. Overcharging a battery can cause damage to it, but the Apple engineers have already designed, built, and calibrated the battery charging so that it never charges to 100% of the battery’s full capacity. Plus, with the built in battery management features of macOS, you’re not adding much if anything at all in the way of prolonged battery life.
Or a complete alternative to this is to limit my battery charge to lets say 50% and keep it always plugged in? But I have noticed that the base of the machine alaways remains hot, which again is not good for the battery.
The base remains hot for one of two reasons: continual activation of the charging circuits because your Mac wasn’t designed to use a charging ceiling of 50% and/or you’re using the machine for what it was designed for. Suffice to say, what you interpret as “hot” is well within spec.