Forex Arbitrage Calculations

I need to have all the calculations which are used in the Arbitrage EAs.

This includes:

1. Offset calculations (Price difference in normal quiet market, between fast broker feed and slow broker feed)

2. Gap (Price difference when Arbitrage opportunity arises)

3. Spread calculations (both fast and slow broker spreads)

4. When should a trade be opened.

5. How should a trade be closed.