Replaceable vs rechargeable batteries gets hotly debated here often. I am in the replaceable camp, but there are arguments for both sides.
The advantage of the replaceable is that short of forgetting to bring spare batteries on a trip, you are never out of power. A rechargeable when you forget to plug them in, or if the battery capacity starts to fail, can leave you in a jam. And when you travel, you have to remember to pack your charger and have a place to plug it in. Then there is the issue of drying the aids each day. Some rechargers dry your aids when they recharge them, and some do not. I believe in the KISS (keep it simple stupid) principal, and like the replaceable battery option. At Costco most of the aids beside the KS9 are available as rechargeable if you want to go that way - Rexton, ReSound, Phillips. They cost more however than you will ever save in battery costs. Battery cost at Costco is about $8 for 48.
The software I use is for the Rexton that they carry, and the specific one I used for your graph would be essentially the Rexton Adore. It was also used for the KS8 which is what I have. Each manufacturer has their own software, but they all basically do the same thing.
Most brands have Standard (S), Medium power (M), Power ( P ) and High Power (HP) receivers. I believe the KS9 (Phonak Marvel) has essentially the same power ratings. One issue to consider is that the S, M, and P receivers most often use off the shelf fittings (open, closed), while the HP receiver has to be molded into a custom mold for the ear. That adds about $40 to the cost of an aid that uses an HP receiver. I think you could get away with an off the shelf fitting for your right ear, but would be better off with a custom mold for your left ear.
In one brand you can have one power receiver and one fitting type in one ear, and a different power receiver and different fitting type in the other ear. The software can handle that. I noticed when I looked at the KS9 datasheet that they use the designations of S, M, P, and UP. They give the current draw of each, and there does not seem to be that much difference, so I may be exaggerating the differences in battery life. I have M receivers in the KS8 (Rexton/Signia) and get pretty close to 5.5 days life with a 312. I do some streaming, and use a smartphone. Without streaming and a smartphone battery life will be longer.
Costco does not pay commission and there should be no sales pressure to buy more than what you need. One decision that you will have to make is whether or not you want custom molds or not, as that is an extra cost ($40 per ear or so). If you want the UP receiver in the KS9 you probably will have to go for the custom mold for the left ear. Optional whether or not you go for a mold in the right ear. Some feel they fit better, and some do not.