It is almost guaranteed that I pay less to drive my 2005 Honda CR-V (paid entirely with taxable dollars) than a business owner pays to lease a newer Honda CR-V paid with pre-tax dollars. (So, that's one reason why you might not lease a car for your business.)

1) This may not be true. In most countries you would get a capital allowance that means you could make this saving even if you buy the car outright. There are also different kinds of lease that have different tax effects. In the UK VAT on a contract hire is 50% disallowed if you use the car personally for instance. Another reason this might be a bad idea, driving the companies car for personal use may be a 'benefit in kind' and taxable at a high rate. In many situations it is better to buy the car personally and record business miles and claim it on expenses at a government approved rate per mile. Talk to an accountant, it depends on several factors.

2) Many countries have minimum wage legislation. Don't pay less than that!

3) This is far too general to be true. If you can afford it and are planning an exit then leaving profits in a company can be great. This presumes that there is no better user for the money, which is not something you can generalize about.

Disclosure: I'm in Finance, but not a tax specialist.