Pumping question? Please help

Ira
I am EBF. But I want to keep a bottle of pumped milk just in case I am stuck with something else so my husband can feed the baby. I don't know but I find pumping to be a lot of hassle😫.sorry for too many questions. Any tips would be really appreciated 
1)when should I pump? And ideally how long should I pump
2)I plan to feed the baby maybe once or twice in a day through bottle. Will it decrease my supply? I am really scared about it
3)how do I store the milk for the day?
4) also if I want to store milk for future use how should I store it?