I may not be able to give you all answers but few.
Product status - Did you check this link on Product status. This link talks about mantaining product status inetrnally and externally. This should solve your purpose
Product Not searchable - I think you can go to your Index and goto Exclude section and define the path to the link. This will make sure that your that particular Product wil not be indexed by Kentico's Lucene Indexer.
Adding a product - I am not sure if this could be achieved using macros out of the box. You will need to check the Basket Value when a product is added to see if the amount is equla to or exceeds a certain value
ECommerceContext.CurrentShoppingCart.TotalItemsPrice > 100
Then use a trigger to add this new Product using SKU's?
This example might help you - Shopping Carts