I've got six (I think) open 1/2" hose ports on the engine and the two vent hoses from the fuel tank. How can I figure out what hose goes to what port and where I need to route the hoses?

1/2 inch==approx 13mm.....2 could be head breather. others i dunno.

If we knew what engine it would healp greatly. I suppose it's a 1.7 so here is a diagram for starters.

Oops... 1.7L that PO converted to single carburetor (yuck). Still have the FI parts so maybe convert back. Since the FI hardware is not installed, some of the ports in the diagram are not there any more. In general... what's got positive pressure and what's got negative? The blower port is positive and the crankcase/intake ports are negative?

yup...

blower=+
intake=-
crankcase=0/+ depends on how worn the engine is.....mine is kinda pressurized but i think i know why

here's what i did:
got three lengths of hose and a 1/2 inch T....
connected the head ports to the T built into the engine, and then used the T to connect the pcv system (next to the oil filler)
plumbed it all to the carb and it's set.