A. Zakat is due on:

Gold and silver, including ornaments or jewellery containing gold and/or silver.
Cash held at home or in bank accounts.
Stocks and shares owned either directly or through investment funds.
Money lent to others.
Business stock in trade and merchandise.
Agricultural produce.
Livestock animals such as cows, goats and sheep.
Pensions.
Property owned for investment purposes.

A. Zakat is due a year after your level of personal wealth has reached the Nisab threshold. In order to remain eligible to pay Zakat, your level of excess wealth should remain higher than the Nisab for a full lunar year. 

For example, if your level of expendable wealth exceeds the total Nisab value in the month of Ramadan, your payment will not be due until the following Ramadan, so long as your personal wealth remains above the threshold.

If at any time your wealth drops below the level of Nisab, you would cease being eligible to give Zakat. Once your wealth increases to the Nisab level, you would begin counting 12 lunar months from that point onwards.

A. Zakat can be paid in monthly instalments. To do this, divide the total amount of Zakat owed by 12 and set up a regular payment with Muslim Hands specifying Zakat as the type of donation.

Sponsoring an orphan is also another good way to give your Zakat on a monthly basis.

A. There are eight categories as outlined in the Qur’an:

The poor, those in debt, the wayfarer, those in the cause of Allah (SWT), the needy, those whose hearts are to be reconciled, to free those in captivity and those who collect and distribute Zakat payments.

A. If you have not paid Zakat from previous years in which you were eligible to do so, you must pay what you owe as soon as possible.

Missed Zakat would be calculated in the same way you calculate your current Zakat - however, you would use the Nisab value from the missed Zakat year, as opposed to the current Nisab value.