Most of the time it breaks off and you will need to drill it out and replace screew.
Tools that have rusted can be cleaned with a piece of steel wool without ruining the finish. A product called Liquid Wrench can also be used to clean rusted tools.
Keep it soaked with penetrating oil and wait and/or gently apply heat to the base of the distributor.
Hit it with a hammer
Hacksaw
A cutting torch is one answer.
Put in Hot water
Bad news. I have found it impossible to remove the bolt caps without breaking them. They are mortared on. They do make plastic bolt caps in a lot of different colors.
A magnet
a large hammer
Rusting bolts normally indicates that the bolts are brittle. Taking a pair of water pump pliers and squeezing really hard will most of the time break the rusted bolt so you can remove the toilet seat. Otherwise depending on the type of toilet seat installed, you can drill a hole right through exactly where the rusted bolts slot in, so helping you remove the toilet seat.
Lug nuts are still on, wheel is rusted to the hub.
Your going to need to get a special puller if its rusted on, usually if its new or not rusty you can just remove the bolt and hit it with a hammer a few times and it will come right off but if it is rusted then you should get a crankshaft dampner puller