Gerard, you're right with the first 2! Von Trips did race under an alias, but not in F1. His alias was Axel Linther, and he used it racing Porsches in the German Championship. Both drivers used an alias to hide their racing careers from their families.
You can read a Von Trips bio at:
http://www.erftkreis-online.de/servi...iographie.html
About Larrousse and Hill: what I was looking for, was that they both used uncompetitive works Lola-chassis, before switching to, even uncompetitive, own designs.
I'll give hints for the remaining two:
3: these drivers are linked through 4 seasons: 1958, 1982 and 1986/1987.
4: these tracks are linked by 2 drivers.