Part 1:
When SM came out, we asked our TA to price the new rates for 3 cruises booked under OLife, so we could compare $ for $ whether it made sense for us. We took into account the price of our OLife excursions, the cost of the basic beverage package included in SM and the cost of the second WiFi included with SM. We had some SBC included from O (not our TA's SBC) to fold into the calculation. Our TA found that in one case, we qualified for a new sale price, and the new price saved us several thousands of $, so we switched. In the cases of other 2, there was a loss, primarily because we would lose some bonus SBC from O, so we didn't switch. The important point here is our TA was a savvy agent who could lay out the difference.
Part 2:
I'm not sure exactly what you were trying to say, but under OLife you get a fixed number of included excursions which were included in the OLife fare and which were priced at $100 each above the cruise only fare. If you exceeded that number by enough to qualify to the 25% discount, it would apply to all. The ones selected for the OLife excursions counted towards the number needed for the discount.
In the case of SM, you get a fixed $ amount to spend. If the number of excursions selected reach the minimum number, you would get a 25% discount on all selected. The fixed amount go towards the reduced total.
Do that clarify it for you?