'help out' is informal and more restricted in meaning than help it is often used when asking for or offering aid/assistance with a task or when the 'help' in question is financial e.g. 'I offered to help him out with the course fees.' - I offered to lend/give him part or all of the money to pay for the course fees.
'help out' cannot be used as a noun.
There are no other prepositions that can be added to 'help' in this way
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