Are civilian/GA pilots expected to "see and avoid" fast military jets in VMC?
It is both parties responsibility to see-and-avoid, but it does help to know where you are more likely to find high speed military activity and high performance maneuvering to aid you in seeing and avoiding. 

Military operations in the US are typically confined to military training routes (MTR), military operations areas (MOA), restricted airspace and prohibited airspace.  

The MTRs are low altitude, high speed routes and are charted on sectional charts so you know to be extra vigilant around them or to just avoid them altogether. 

Military operation areas or MOAs are charted and are big boxes with ceiling and floor altitudes.  GA aircraft can query ATC if these are active and in any case they can fly into them.  If a GA aircraft penetrates and active MOA, the military activity is typically stopped until you leave.  General rule of thumb is to just not go there.

Restricted areas are only accessible to you when cold, so there will not be military activity there if you allowed to be there.  

Prohibited airspace may not have military activity before you show up, but certainly will after you do, and you might get to watch an F16 attempt slow flight and form up on your wing.  Remember your intercept procedures for this one.

Any military activity outside of this will generally be typical enroute flying at altitude.  You will occasionally hear ATC coordinating mid-air refueling but that won't be something you have to worry about.