What maps are included with this unit? Are free map updates available as well?

The C-Map Insight Pro maps have pretty good detail.   You get coverage of coastal waters as well as inland lakes.  Here is what they say about it:

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C-MAP Insight Pro covers the entire US Inland and Coastal areas on a single SD card and includes:

• High definition 1-3’ depth contours for thousands of lakes
• Fishing HotSpots POIs, lake-specific fishing tips and techniques
• Harbor charts & Port Info
• State fish and wildlife regulations/records
• Active Captain crowd-sourced POIs

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There are no included updates.