1) I think it's best if you use the slider you're currently using to link to these pages as they are your main topics. However, you can also create a Dynamic Template using the Template Builder, this will allow you to include pages, columns, rulers, .. as in the demo shown here.
For example, you can create a page called "Listings" and include it using the Template Builder. In your listings page you can use shortcodes with the magic wand tool. Here's an example of the dummy content you can generate through your options panel:
[dropcap2]1[/dropcap2]The theme uses a flexible template system that enables you to create stunning pages out of the box with no coding knowledge at all
[dropcap3]2[/dropcap3]The theme comes with several predefined skin options but also utilizes a color and background image switcher, a font-switch for headings and several other layout options.
[dropcap3]3[/dropcap3]You can now setup a wordpress installation that looks like this demo with just a single click of your mouse. Amazing to get started and accustomed to the theme.
[dropcap3]4[/dropcap3]To get your content displayed properly the theme uses wordpress shortcodes. Visual previews help you while creating those shortcodes so you don't need to memorize the codes :)
[iconbox title="Shortcodes" icon="edit-paste.png"]Select one of the icons. You can add icons to this list by simply uploading new ones to your themes image folder .[/iconbox]
[iconbox title="Smart Ideas" icon="dialog-information.png"]Folder (images/icons/iconbox). They will be displayed here automatically
[iconbox title="Copy Paste Work" icon="edit-copy.png"]Select one of the icons. You can add icons to this list by simply uploading new ones to your themes image folder .[/iconbox]
[iconbox title="Reviews" icon="edit-find.png"]Folder (images/icons/iconbox). They will be displayed here automatically
2) As far as I'm aware the used function doesn't easily allow to only include specified posts. After all, a related posts widget/plugin is meant to automatically show posts related to the post you're on without a lot of extra work.
Alternatively you can always use shortcodes to display columns and link to other pages you think are related.
3) I don't have much experience with map plugins, however this plugin looks promising.
I hope this helps.