It depends on what is being asked - is this about the past or the future?

WERE - This is a hypothetical situation in the future. For example, 'If the current owner WERE allowed to have an auto body shop, she could make a lot of money from her business.'

WAS - This is something that might or might not have happened in the past. For example, 'If the current owner WAS allowed to have an auto body shop, but now he is not, I wonder who cancelled his permit?'

'Much' is a word that is used for things that require a specific unit of measurement. For example, it is meaningless to ask for '5 gasolines.' Instead, you must ask for '5 gallons of gasoline.' Because of this, 'much' can be used with 'gasoline.' So you can have 'too much gasoline,' but it makes no sense to have 'too many gasolines.'

On the other hand, 'many' is a word that is used for things to do not require a specific unit of measurement. For example, you can have '5 eggs.' No unit of measurement is needed other than the item itself. Because of this, 'many' can be used with 'eggs.' So you can have 'too many eggs', but you can't have 'too much eggs.'

So 'five eggs is too much' is wrong, just like 'too much eggs,' whereas 'five eggs is too many' isright, just like 'too many eggs.'

As for 'Five eggs are too many', it doesn't sound right to me either, but I don't have a great explanation for it.