I'm trying to understand the workflow described in the docs for creating a proposed transaction for a simple transfer.

On the testnet, first I did this:
begin_builder_transaction
I got 0 as the Handle ID, so I did the next step: 
add_operation_to_builder_transaction 0 [0,{"from": "1.2.41","to": "1.2.51","amount": {"amount": 7777774,"asset_id": "1.3.0"}}]
which went through without errors.

Now, when I do this:
propose_builder_transaction 0 "2016-01-27T00:00:00" 36000 false
there is no error.

But when I try to broadcast it:
propose_builder_transaction 0 "2016-01-27T00:00:00" 36000 true
I get this error:

0 exception: unspecified
3030006 invalid_committee_approval: committee account cannot directly approve transaction
Committee account may only propose transactions


(1) Why is this happening?
How can I propose a transaction without broadcasting the proposal first?

(2) How do I get hold of the Proposal ID, so that the other party can approve the proposal?

(3) The CLI command propose_builder_transaction2 seems to be no longer available.
Can I use propose_builder_transaction instead?
What is the difference between propose_builder_transaction and propose_builder_transaction2?