Suitability of disconnect switch
#1 is it normal to have a 100A-breakered panel  downline of 60A overcurrent protection?  Totally legal. But I'd use a 225A panel.  One thing many of us here agree on is running out of panel spaces is bad, and panel spaces are cheap.  Both better and cheaper to get a 42-space panel today and only ever use 18 spaces, then get a 12-space panel today have to retrofit a 20-space panel tomorrow and a 30-space panel later still when you add an electric car -- that's just dumb.  The big panels we prefer come with big 150-225A breakers, and they often come with "bonus breakers" and ground bars included, so the extra cost can be a wash.

#2 Breakers and fuses protect wiring downstream. Without the 60A fuse, the jumper into your house (#6?) would have no overload protection at all, and if the cable became shorted, nothing would interrupt current and it would burn your house down.  

#3 If you want to increase service above 60A, talk to your power company  Your service capacity will be limited by the lowest of 


what the power company is willing to provide
the ampacity of your service conductors (frop top of service-drop pole to shutoff switch, which size using the service-conductor rules). 
the ampacity of your feeder from shutoff switch to main panel (using feeder sizing rules). 
the max ampacity of your meter pan
the max ampacity of your shutoff switch.  


It's possible to get combination meter pans/main breakers, with the main breaker serving as the shutoff switch and replacing the fuses.  The main breaker and the feeder rules decides the wire size downstream of that breaker. 



As far as where is the main grounding point located, some sticklers say the grounding point must be the outside fusing/shutoff switch.  However that is awkward in your situation, and for ground-siting purposes I am very comfortable disregarding the outside shutoff and putting the grounding hub in the main panel.  They're built for that, and shutoff switches are not.

This presumes there is one main panel. If you fork lines to two panels off that outdoor switch/breaker, things get really complicated.