Hi T.D. and welcome,
First things first,
to make good coffee you must have fresh beans, and a good grinder.
I am not familiar with the Krups unit that you have, does it have an inbuilt grinder, or do you have a separate grinder?, If not there are several that are suitable for reasonable cost and upwards.
Now that you have freshly ground beans,
I believe the standard is around 30 pounds tamp, BUT all things come back to what does it taste like in the cup..
Tamp pressure can be adjusted depending on grind size, amount of ground coffee, and yes type of filter basket.
Amount of grind for double basket, start with 14 grams, again it depends on what it tastes like, it is not uncommon to use more, but start there.
Is it worth replacing the pressurised baskets, YES.
Again I dont know what you can get that will fit, but a non pressurised basket, or filter, will enable you to more easily tell what is going on when you brew your shots.
I started with a basic Breville thermoblock machine, the difference with fresh beans, a good grinder and non-pressurised filter was significant, and I could produce as good a drink as that machine was capable of.
Also warm up time does make a difference on all machines, 30 mins minimum is good, and not difficult if you get into habit of turning machine on before you want to brew, and then doing something else for a while.
Hope this helps you get started.