A few questions(2)

1. Is it possible to add 2 of the same xtals to the same equipment? For example,if I had a double slotted philosopher's ring,would I be able to add 2 golden potum xtals to it?
2. What is the easiest/cheapest/fastest way to refine a double slotted equipment?
3. What is the drop rate of equipments from bosses? And how much does it increase during the weekly drop boost? Does the stat Luk affect it in any way at all?
4. I've heard many people talk about how awesome the magic skill magic:finale is. With 1 int,it does great damage,right? So,what exactly is this amount of damage? I mean,with the lowest/worst stats and equipments,how much damage would it deal to a level 100+ boss? In average,how much damage does it do?
5. What is the total amount of orbs needed to max out ALL of sololo's or any other general store npc's item storage slots? I've heard that these item storages can go up to S ; is that actually true? For example,everyone has item storage:A open to deposit items and other stuffs. Then,you can add some slots in item storage:A using 1 orb for 5 slots. After the item storage:A has no more slots to add or before that,you can buy item storage:B for 10 orbs. So,in this manner,how many item storages can you open at most? After opening all of them,what would be the item storage slot number? And how many orbs will you need to open them all?
6. If you go to the production menu from stats,at the bottom left of the screen, there's a saying like,"Bag expansion : 2x limit"-does this mean that my production limit will be doubled if I expand my bag? Now,the question is,how do you expand your bag so that your production limit doubles? My current production limit is 49k. So,in order to double the limit,I added a slot to my bag using an orb. My bag's slots did increase by 1. However,my production limit is still the same. So,how can I double my production limit? Is that even possible?