First and foremost, you should know that the legal restrictions on laser pointers are not enforced. Therefore you should not assume the class labelling is correct. One study found that 90% of green lasers in the US had an illegally high power level.
You also should not assume the power rating is correct. It says 5mW probably because that's the most desired power level that consumers want: As bright as possible without being obviously illegal. But really it could be 2mW, or 10mW, or who knows.
Every laser pointer is dangerous, is not a toy, and should not be pointed anywhere close to other people ...but it takes extreme and unusual bad luck to cause permanent eye damage if its labeling is correct and it is really under 5mW (Note: I am talking specifically about visible-light, continuous-wave green lasers here). Here is a literature review, and you'll see that some injuries were indeed caused by laser pointers with less than 5mW of power, but most were injured by much more powerful lasers, like 30mW and higher.
Best is to find, buy, or borrow a light power meter. They're not expensive, and they're fun to have anyway.
Finally, stepping back, the review cited above found 111 patients with eye injuries from green laser pointers. Given how many green laser pointers are around, I wouldn't consider owning a legally-compliant green laser pointer to be a notably risky activity, compared to other day-to-day risks.
Owning a super-bright one (e.g. 30mW or higher) is something I would consider awfully risky. Treat a super-bright green laser pointer just like you would treat a circular saw: You store it well out of reach of children (and out of reach of irresponsible adults!), you leave it unplugged / remove the batteries when it's not in use, you don't use it if you're drunk, you don't have fun with it, etc. etc. etc.
The Poynting vector $\vec{N}$ is the power per unit area of your beam.
If the beam is perfectly absorbed, then the force is given by
$$ F = \frac{1}{c} \int \vec{N} \cdot d\vec{A}$$
So, providing you have the beam incident normally upon something, the force on it will just be the power of the laser divided by the speed of light.
Of course, if the light is reflected, then you have more force. In the limit of a perfect, specular reflection, the force is doubled.
If what you mean is, suppose I have a laser pointer suspended in space and I turn it on; What is the apparent accelerating force on the laser pointer? The answer is exactly the same as above. Power divided by the speed of light.
Best Answer
No, laser light is not necessarily polarized.
There are many different types of lasers. In gas lasers, many different modes may be excited in the cavity, but only modes that are not very lossy end up being amplified and emitted - this can result in a single polarization. However, there may be multiple modes with different polarizations that have this property, resulting in a more random polarization. There also may or may not be a polarizing filter built in to the laser aperture. I don't know as much about other types of lasers, but I don't think they all are necessarily polarized.
You could test whether or not your laser is polarized by getting a polarizing film (for example polarized sunglasses). Shine the laser through the film while rotating the film. If the intensity of the transmitted beam changes when you rotate the film, then it is at least partially polarized.