you can drive up to Panama, and from there you have to take a boat from the port of Portobelo to the port of Cartagena in Colombia. The road connection between Central and South America is interrupted by the so called "Darien Gap", which is the densest jungle in the water, and it is also a restricted area.
Yes, you will have to take the Panamerican Hwy that goes from Canada all the way down to the tip of South America. You will have to check visa status for each country. I will not say is the safest thing to do because it isn't. Mexico is a bad area to drive through as lots of drug cartel and gang activity. Guatemala, El Salvador and Honduras are dangerous. Honduras being the worse as it is the number 1 murder country in the world.
I'm sure you could. The gentleman put up the link about the darien gap, but there must be a ferry service you can take around it.
But in case you have been living under a rock for the past decade - the drug gangs in Mexico are pretty hostile. Plus you'd have to be careful in other parts of central america too. For these reasons I would highly advise you not to even attempt this. just with in the past year a marine on leave was kidnapped in mexico while on his way to Costa Rica for surfing. If his case hadn't made the media he'd probably still be there. They let him go. If they got you would you be able to get the kind of coverage he got or be able to pay the ransom?
Don't even consider it.
No...there is no highway that goes all the way through. See site below and read the details.
If you want.
