Zakaat

Including the wealth one acquired on one's zakaat day in one's zakaat calculation

Q: My zakaat date is on the first of Ramadhaan. At which time will I have to take an account to work out my zakaat, as during the day, I will also be doing trade. Hence, if I buy and sell during the day, will I include the wealth I acquire on that day in my zakaat calculation? Similarly, if I incur debts during the day, will I deduct the debts from my zakaat calculation?

Calculating zakaat according to the nisaab of gold and silver

Q: If in 2017 and 2018 a person followed the silver nisab but happened to not pay Zakah in those years despite meeting the silver Nisaab then at a later point (maybe 2018 onwards) he moved to the gold nisaab and when he did calculation for past Zakah, he used the gold nisaab retroactively, even for those years where he followed silver nisaab but that meant for those years he did not owe Zakah according to gold nisaab. Would he be required to still pay Zakah for those two years because at the time of those two years he was following silver nisaab?