Dignity,
If you have the information in a file (csv), then you can probably use GPSU to convert it to a GPX format and then import it into home port. or you can copy and past each location, via the above method (create a way point). If you need a bit of assistance let me know.
PHil, without the map card in the card reader, you wont get access to the fishing maps. but with mapsource installed on the same PC you can access the mapsource maps..
Yes I still find Mapsource better than Homeport, though if you put some time it to it, it will do what you need it too relatively simply.
Yes, you can power your 750 via a 12v laptop power supply and a power connector for your unit. I have one it cost $45 for the garmin power cable and the laptop power supply I sourced from Trymax.
Regards
Honda.