Well you're using the conservative definition of small government (except for the military; the idea the we should have a strong military is technically liberal because it is a tax increase to provide increased government service, though a pure liberal would be less likely to use the military as he'd see it as a violation of individual liberties). The conservative definition of a small govenrment involves low taxes, low spending, low services, low regulations on businesses, etc. Taxation and business regulations are only one piece of the government's power.
The other piece of the government's power is to pass criminal laws and regulate moral disputes. The more crimes a government creates and the more a government forces people to live in a certain way, the more government is preventing people from living the way they want. For example, government which stops young people from seeing movies is a larger government than the same government which does not. A government which forces one man to be a slave to another is a larger government than one which does not. In this case, increased size of the government doesn't mean increased taxes, and it doesn't always mean increased paperwork, but it does always mean the government has increased control over how individuals live their lives. One government might control people so much that they are allowed only to wake up, go to work for 16 hours, then come home and go to sleep. Another government might allow people to do anything they want, including hurt other people. A government which is so large that it controls enough aspects of a person's life that their standard of living is decreased is called a tyranny.
This is true. They agree on half of the role of the government: the fiscal half. On the other hand, they also disagree on half: the moral half. Conservatives want a government that controls people, Libertarians want a government that doesn't. Populists are the opposite of Libertarians, and they also agree with Conservatives on half the issues.
But Liberals are the opposite of Conservatives, and they agree with Libertarians on half the issues as well.
I think a lot of people who are into politics think that Libertarians are more in agreement with themselves than with their opponents. I think this because I think liberals tend to care more about moral issues (abortion, gay rights, freedom of speech, freedom of religion) while conservatives tend to care more about fiscal issues (less taxes, flatter tax rates, less restrictions on businesses).