1. I assume you're concerned about a min spec for gaming. It's not a rule set in stone. If you're a fraction of a ghz under min spec, it'll probably be fine, it's just you may have a touch more stutter, or slightly lower FPS, in some parts. What's the game out of curiousity?
3. I wouldn't recommend a tool. I'd recommend reading and learning how to do it without a tool. Google has plenty of how-tos. It depends on whether you BIOS allows you access to those settings. If it doesn't, you will probably have to use a tool. I see
CPU-Z being recommended. I've never heard of it nor used it.
But basically, you're going to have to do research and reading anyways. You should not go into this blind. You're going to need to research your mobo specs, and you're going to need to research your CPU specs. Not doing that is a recipe for fucking everything up. So since you've already got that intellectual burden, you might as well go the full 9 and read about doing your overclock through the BIOS, so you understand the underlying math.
If you're doing it manually, usually you go into your BIOS and adjust the Front Side Bus Speed the motherboard is running at. This is effectively how "hot" the mobo is running the CPU. There is a calculation you do using the FSB speed that is essentially FSB x something (I forget what, it's been a long time since I've oc'd) which lets you arrive at your final operating ghz.
The reason overclocking is dangerous is, if you do the math wrong and set your FSB to something high that blows out your processor's capacity, you might damage it. But more likely, your computer will just fail to boot at all. It will probably POST then shit itself. And then you're locked out and have to do shenanigans to reset your BIOS to a factory state where it will boot again. (Which is about 5x more difficult in a laptop then a desktop. And then you mail to the manufacturer, they see what you did and charge you several hundred dollars to get your laptop back to where it should be.)
So that's why I _highly_ encourage you to actually read some guides on overclocking before you go fooling with a tool, because a tool makes it very easy to shoot yourself in the foot, and in doing your research you'll get a lot of "don't do this, this or that" advice.