What are options for applying non-inventory costs to production orders?

Question

We have a non-inventory costs that need to be assigned to product produced on production orders.  There are two processes -make-to-order and make-to-stock.
Currently we use activity rates to apply labor and burden costs to our production.  We use separate cost centers where needed to ensure that we have sufficient granularity to our activity rates applied.
We have a few specific issues where we need to understand the options for applying costs -
1) We have freight and duty costs related to inbound raw material that we want to assign to our final product.  The amount assigned may be either a specific amount (or a specific amount per model), or a % of the total cost on that production order.
2) We have material on the production order bill of material that is called out by quantity and we are using discrete backflush, however we have found there are issues with the accuracy of the quantities.  We want to have this product ordered using KANBAN (bin ordering) and have the value relieved from inventory when the bin is issued to production.  The cost on the production order is envisioned to be an average amount for the product - or an average amount by model.
3) We want to have a portion of cost for production scrap included in the cost of each product produced. (similar to freight and duty).
In all cases- the amount can change depending on analysis from accounting regarding freight and duty costs (these fluctuate depending on the cost savings we achieve with combined loads and depending on the amount of out of country sourcing), the scrap amount may change periodically depending on the initiatives to reduce scrap on the production floor, etc.
We currently use three activity types, labor, burden and tooling.  It is my understanding that there is a limitation in SAP that keeps us limited to 6 activity types.
My questions are:
Are we limited on activity types? these are an option to apply additional costs, but may not be the best option if we want to change the amount applied based on model or apply as a percentage.
Are there other options for applying costs that we can explore? I want to be sure we take into account the various options available before we start down a specific path.
Thank you in advance for your assistance.

Answer 1

As clarification- we are using standard costing for our raw material.  We currently accumulate the incoming freight in a balance sheet account.  This is treated as part of our inventory.  We have considered using an activity type with a activity added to the BOM to apply the cost to the production order.  Then we could use the secondarly cost element data to book an entry to relieve the freight account on the balance sheet.
Because we use standard costing- access to see production order variance is critical and must be maintained in any process we select. We also use COPA reporting- so the costing information must be able to flow to COPA for the specific orders/products/serial numbers.
We are doing make to order (production order / sales order specific combination) but also looking at a make to stock process - so the method to apply costs must take both of these configurations into consideration.
Rajneesh - you mentioned that I am limited to 6 activities in a work center- but does that mean I can have more than 6 activity types in SAP but only 6 activities in a work center/cost center combination?
Thank you.