They're all good points.
The challenge is that MPs don't spend government money, they spend other people's.
If other people don't want to pay more tax, then there are no additional services. It doesn't matter how much serving an MP is inclined to do.
It's this challenge that underpins government spending initiatives.
An MP must juggle the expenditure around the wants and needs of the whole electorate, not just the 'most needy'.
I think the idea that all the government money is being 'wasted' is not true: I think you'll find that most cash is very tightly earmarked, and that in fact there's very little flexibility at all.
If you don't agree, why don't you take a much closer interest?
Here's a great exercise in environmental stability
. You play the Prime Minister and try to balance the books.
Remember that if you try and reduce manufacturing or consumption by much you'll end up with strikes, riots and a recession
It's very very difficult!