Zakah on Wealth

 Assalamu alaikum.i have some questions about zakat on wealth (not zakat alfitr): basically every year on the last day of ramadan, i calculate all the wealth i have (in cash, stocks, and wife's gold holding) and apply the 2.5% to calculate the zakat.however as i live in belgium, i usually send the money to my dad in lebanon and he distributes to needy relatives (not direct parents or descendents of mine). that means the money is actually payed later than the last day of ramadan when i calculate my zakat. recently i found some articles that say zakat shouldn't be delayed and should be payed on the day it reaches the hawl (1 year).so the questions are: 1- can the day zakat is calculated on be different than the day it's paid?. i remember i read somewhere that i have upto 1 year (before next zakat calculation) to pay it. is this correct?2- if this isn't correct, it's very hard for me to do the calculations all in one day and pay the zakat. reason is that i have to wait until stock market closes to get the exact value of my stocks, also i have to find out the value of gold on that day, and then i have to ask my dad to pay the money from his bank account while i transfer this to him.3-if the value of my stocks went below the nisab during the current year, do i still have to pay zakat on it?4- some of my individual stocks were below the nisab this year, do i calculate the zakat on each individual stock which was above the nisab? or this is not allowed and i should calculate the total worth of the stocks and pay zakat on that?Jazakum Allah khayran. Fadi.