Build a Wordpress Plugin to display a Google Map with markers, only loading and showing the markers in the visible area of the map.

I need a wordpress plugin writing using correct wordpress plugin architecture. The reason for this plugin development is to increase the speed of map rendering. I have Custom Posts created by Toolset (wp-types) and these posts are Marinas with custom fields that include their Latitude and Longitude. I have many thousands of Marinas and so I only want to load the markers on a Google map that show at a certain zoom level in the visible portion of the map. So for example I have 7000 posts for the USA and I only want the map to start loading markers when firstly the user is at or below a certain zoom level. This zoom level will be set either by a field on the custom post or by a setting in the plugin administration. The zoom level in the custom post will be the master zoom level. The map should only load a maximum of 200 markers. The number 200 should be a plugin variable that can be changed in the plugin Admin. The map must use marker clustering and the boundaries for this must be settings in the Administration of the plugin. The marker image should be located using a box in the plugin administration. If the maximum number of markers is achieved then a warning box must overlay and advise the user to zoom in closer. The content of this warning window should be a setting in the plugin administration. The markers should all have info windows that take information from the custom post and link to the custom post page on the site. I have attached an image of this info window. The map should be able to re-size depending on viewport size. The map should have Roadmap and Satellite controls and a setting in the Admin should allow the administrator to set the default map type. Google Map API Key has been obtained. There are other mapping plugins on this site so duplicate loading of javascript files should be tested for and avoided. The map should be able to be displayed using a shortcode. The current website is [login to view URL]