To develop a custom indicator for MT4

I have data and HTML5 widgets which I wish to supply to a broker within their MT4 environment. The job is split in two.

1. I wish to display a widget that displays my data for users of a broker. This widget will reflect data on a currency pair, and so if possible shall change depending on the currency pair being viewed by the user. The widgets must be made available to all users of a certain broker.

2. I have an XML data feed that is a simply a numeric reference. This data needs to be plotted ontop of the price in the charts of MT4. The user then must be able to perform analysis of my data within the chart, such as intersecting moving averages and other technical indicators. The first part I assume will come as an Custom Indicator, but I am unsure how to create the second part.