My 2 cents answer (might be wrong, sorry, someone pls validate)

1. Assuming you use Pos Malaysia, you can check out their website to determine the cost. Also, pls bear in mind, they are going to increase postage effective Jun/ Jul
2. Parcel
3. Total weight of your parcel, ie your T-shirt plus whatever packaging cost you have
4. As name said, registered, someone got to signed to acknowledge they received the parcel. For tracking purposes.
5. Sorry, this one I dont know.


And final opinion, depends on your volume, you might interested to get those long term arragement with those private courier co, who know, they might even offered cheaper rate than Post Malaysia