Several websites that are useful concerning microphones and recorders:
primarily radio production, but has some tests of portable recorders:
audio for video:
Audio professionals, including a lot of audio for video:
tests of some mics used for video production (probably much higher end than you are considering, but there are samples so you can hear what high quality microphones sound like):
For connecting the AT897 or the NTG-2 microphone to your camcorder, you don't want an attenuating cable, you want an impedance matching cable. Bill provided URLs to such cables, but at one point referred to them as attenuating transformer cables. You don't want attenuation, and if you just use a regular XLR to 3.5 mm cable, without impedance matching, you will end up with serious attenuation. The cable with impedance matching transformer greatly diminishes any attenuation.
If you spend some time at the various audio websites, you will quickly learn that for serious sound the worst location for a microphone is mounted on the camcorder. There are some situations, such as run and gun, where you have to compromise and mount the microphone on the camcorder. But if you are serious about sound, you will realize that correct microphone placement for the individual situation is paramount. An inexpensive portable audio recorder placed at the right location can easily outperform a $2000 Schoeps microphone placed at the wrong location. Depending on your shooting situation, simply placing a more expensive microphone on top of your camcorder might simply be a waste of money. Perhaps you could state what camcorder you are using and what type off shooting situations you expect, and then more detailed responses could be given.
You didn't mention which camcorder you have. Most camcorders have lousy audio circuitry and noisy preamps when using external microphones. You generally have to go to higher level prosumer or professional camcorders to have XLR inputs and high quality preamps.
As for audio recorders, the DR-40 is a step above the DR-05, mainly because it has XLR inputs. However, its mic preamps are not really quiet, especially when using low output microphones. If you want XLR inputs and quieter preamps, consider the DR-100 mkII. See the Transom website for tests of the DR-100 and DR-40. If you want quiet preamps in a small package, and you don't need XLR inputs, the Sony PCM-M10 is widely regarded as the least expensive quiet preamp small size portable audio recorder.
Generally you get what you pay for, but in the case of the AT3350, I am surprised at the quality of the sound for a $17 microphone. Many inexpensive microphones are very noisy, but the AT3350 is decent, considering its cost, especially if you don't need XLR. I own much more expensive XLR microphones, including lavaliers, and I would not be embarrassed to use the AT3350 in some cases.
Many consumer camcorders are capable of creating great images with good lighting, but the sound is usually so-so. People are surprised to find that they might have to spend several times the cost of their camcorder on microphones, a mixer and a recorder to obtain sound quality on a par with the picture quality from inexpensive camcorders. Simply having good equipment is not enough - you need to develop experience in how to properly use it.
With audio equipment, you have to be careful to not buy equipment that is not high enough quality for your needs, nor to buy equipment that is overkill for your needs. I know from experience, as I have done both. Fortunately, unlike consumer camcorders, quality microphones, mixers and high end recorders tend to hold their value and can fairly easily be re-sold. Good luck with your project.