The VATs are collected at the point of sale as a percentage of the transaction with any difference being that the VATs will typically tax business to business purchases while the FairTax does not. That makes the VATs a cascading tax that boosts prices which the FairTax does not do.
The method of calculation is simple for either tax but the FairTax is superior since it doesn’t enforce the bureaucratic mess (and evasion opportunity) of applying to the government to plead your case for a refund of overpaid amounts. Both are vastly easier to calculate and collect than an income tax system.
Yes, but it's smaller at the point of sale since it's collected at each stage along the way. The Fair Tax is a one-time tax at the point of sale and is therefore large.