Aluminum foil dissipates heat very well. It takes a lot of laser power to cut foil, several watts at least. Not a beginner project.
CO2 lasers normally run CW and are not q-switched. If you want a portable pulse laser, get an SSY-1 head (already dye-cell q-switched) from a surplus seller and brush up on your power electronics to build a portable power pack for it. One of these can be made portable and it has been done a few times. These are not projects for anyone new to lasers and electronics. These involve lethal high voltages and currents in their operation.
From your questions, you need to do a lot of reading here, and on Sam's Laser FAQ to get yourself up to speed on lasers, especially laser safety and the need for valid eye protection.
As far as a laser to light matches, cut tape, pop balloons, etc., a 200mW red from 0-like or rayfoss will be fairly cheap and get you started. When you want a little more, consider a 6x or better bluray build, you can get hosts, kits, etc. here on the forum. Get the appropriate goggles for this laser.
As far as a UV or IR at 400mW, cutting and burning depend on the capability of the target material to absorb the frequency of laser light being delivered to the target. An IR at 2W will not burn white paper until it finds a tiny particle of dirt. A bluray at 200mW will easily burn white paper.
All of these questions have been answered here and there in the forum over time. Do some searching, and reading of old relevent threads as well as visiting Sams Laser FAQ.
Please remember that lasers are serious and potentially dangerous devices that are coming under more and more government scrutiny as lasers become more powerful. They require safe useage procedures and the proper safety gear.
