Once you price out the Lavender you may not want to go with an eo, but it is a top seller for me as well, and one of my all time favs. I love the eo scent and have never found a straight lav fo that I liked at all. So I make it and they buy it, but cursing all the way.
I also have a nice clean scent and a citrus, as well as a slightly sweet scent w vanilla that balance out my top four. But I agree that a lot of people like omh too.
As for rosemary, you certainly do not need to worry about someone using a rosemary scented or infused soap. In fact, even eating a small amount of the herb when pregnant is fine. Have you ever heard an OB doc tell you not to eat rosemary with your lamb and mint or not to cook with rosemary? Mine certainly never did. While you do not want to drink a rosemary tea regularly, or eat a lot of rosemary if you are pregnant, the soap is not going to harm you. And I sincerely doubt that even the leave on products would have a high enough concentration to trigger any issues. Everyone wants to cover their butts though, so they just repeat what they once read and what everyone else repeated. Check out what expert Robert Tisserand has to say about rosemary (as well as several other herbs and eo's that carry such "warnings"). He provides the studies that began all the warnings and breaks down the amounts one would need to ingest to cause the problems being discussed. It is very enlightening.
Rosemary has nothing to do with heart conditions, other than the potential to increase blood pressure (which is usually more circulatory in nature). So those with high bp should exercise caution, but again, this is not really an issue in soap or with small amounts. I have high bp and it does not affect me, but this is a possibility, and each person may be different. Your friend is correct though, even the smell alone may or may not, but could possibly trigger a seizure, so it is not worth the risk there. But seizures can also be triggered by lights and white noise, so it isn't because rosemary is so dangerous.
If you change your mind and go for rosemary soap, the max usage rate is 5%. If you want to mix it with a citrus eo, most of those are also 5%. When using more than 1 eo you have to decrease one or both so your max rate is within the range and not doubled. So you would not do 5% for each eo, making total eo's 10%, as that would be too high and potentially irritating.