12. What is better, a subscription (redemption) or a buy order (sell order)?

That depends on the individual.  

Settlement of subscriptions and redemptions may take a few days or weeks to complete. On the other hand, buy and sell orders are settled instantly if they are filled by matching orders.

Investors can subscribe and redeem directly with the fund, while there is no guarantee that orders placed on ADDX secondary exchange will be filled.

The fees involved for subscription/redemption may also be different from secondary trading fees.