I think you got it about right, its in the 100s
Me accurate haha probably not
ballpark well yeah maybe
starter can pull the full cold cranking amps of the battery for a split second, which is a lot.
When it switches on, apart from the small current used by the solenoid the starter acts as nearly a dead short, until it turns, so the current is HUGE.
CCA for car battery:- Must manage somewhere between 250 to 600 amps at 0*C for 30 seconds depending on battery size
a spinning starter draws anything from 90 like a swift or yaris to 200 amps on a v8, a petrol car engine of "sensible" Compression.
i'd be putting the breakers in the battery- to- car circuit and the alternator - to - car circuit. Protect bunches of cables in the loom first over and above the simple big fat single wire run from battery to starter. Its easy to replace and is in most cases on the other side of the bodywork from you... if it burns, its outside...! or if it isn't move it outside on rubber lined clips.
the main loom is inside, its complicated and is a PITA to replace.
1 hot wire ruins the insulation on all others and turns the loom into a stick of rock with a copper core.
breakers to protect this makes some sense although all of it apart from potentially the igntion feed is probably protected by the fuse box
so your breakers are protecting the moderately fat alternater wire and the moderately fat main feed from battery into car...they pass through the firewall. risk of physical damage. makes some sense to add in protection.
Dave
I am going to fit a failsafe on the battery power lead. 
