HP is gloppy, but if you really pound it down into the mold it should be good. You can trim off the bumpy stuff later. Also sodium lactate helps it be a little smoother.
You can use soufle cups for samples. The little plastic ones with lids. Any place like a Smart & Final will have them. As for the jojoba, I think that it's a matter of what you want. Experiment a little until it has the feel you're after.
Hmmm, I guess the water may be oilier. It's getting to winter though and that's a good thing! When I have added clay it has not been a good result. I know some people do it for the skin benefits, but it has never worked out for me. The clay seems to absorb the wet stuff and make it too wet for me. Now that I'm thinking of it maybe the key is to add the clay last?
A little stearic or maybe beeswax would make it harder and last longer. I don't think MP will ever last as long as CP. MP bases are glycerin and they just can't take the moisture.
I've done this with mango and also cocoa and shea. Melt it down in place of the other oils. When they are dry they're harder too. My favorite combo is coconut milk powder and cocoa butter. Very nice!
I have found two things to be helpful with making bath bombs. First I don't use water at all any more. I just use oil. It's more expensive but makes a better bomb to me. Second, when it's just at that point that it sticks together and my brain says "just a little more" I STOP! In the begining I would just add a tiny bit more and they were never right.
Kaybee I have soaped raspberries and white roses, brown sugar, paradise, precious memories, and I think it was the ultimate vanilla. All were amazing, but brown sugar made the best soap. WOW! I have had many others made in soap by others.
Ponte Verde Soap Shoppe has one that looks like what you may be looking for. It's just equal parts shea and aloe gel with preservative though. It would be super easy to make.
Take the weight of the logs and divide by 4. That will tell you how many bars. Then measure out that many sections with a ruler. Not exact, but reasonably close.