grammar questions

I have a few questions about transitive-intransitive verbs:

In order to change a sentence from active to passive there needs to be a transitive verb-the verb has to be followed by an object. But what do we consider objects?

For instance-'The leaves fell to the ground.' We can't make that into a passive sentence but isn't ground an object?

'I usually agree with my sister.' We can't make that into a passive sentence but can't sister be considered an object?

John came to our house is an intransitive sentence. But why can't it be considered a transitive? Isn't house an object?

ALSO- Participal adjectives:

I need to complete the sentence with an -ed or-ing

* If someone steals a car, it is a __________. I think it would be a stolen car. It wouldn't make sense to say it is a stealed car or it is a car stealing. Can you explain this!


* If you plan an event, it is called a planned event. Is this sentence correct?

* If a committee plans something, it is called a ________. Would I write a planned committee or a planning committee?

* If the weather freezes things, it is called freezing weather. Is that correct?

If you break your pencil, you have a _____________. I think it would be broken pencil, but I can't write that. I can only use ed- or ing. A broked pencil doesn't sound right and neither does a breaking pencil.

Can you please explain these to me!