is it ok to update from iOS 4.1 to iOS 4.3.2 directly?

yeah it will be fine

Yes, it should be fine. There's no requirement for installing intermediate updates except where a new update has a requirement of a minimum installed version. Usually that does not apply in a situation such as yours.

If it isn't possible iTunes should refuse to allow the update or recognize that your device is not eligible.

I have no idea. Seems to work OK on mine, but then I'm not that aware of performance changes unless they are quite dramatic.

If you are running 4.2.1 you have absolutely no choice of upgrading to anything in between 4.3.2....

You aren't given a choice.

You have to upgrade to the newest version or nothing else...

The majority of people aren't having any problems with 4.3.2 and I can confirm that I am not having any problems.

Of course nothing is guaranteed.

Actually that's not true. Apple doesn't make it convinent but you can upgrade to any version of firmware you want.

For example...

The firmware for 4.3.1 is still available from Apple but you have to find the link to download it. Fortunately other people have done the heavy lifting. I like www.iphoneheat.com but I've used other sites too. You just need to verify that you're downloading the file from Apple.com

So for 4.3.1 you'd go here: http://www.iphoneheat.com/2011/03/download-ios-4-3-1-firmware-for-iphone-ipad-ip od-touch-ipsw/ and click the link for your device to down load the firmware.

If you look at the link address for iPod Touch 4G you'll see that the download is comming from Apple.com. Here's the link for the 4.3.1 firmware for the 4G touch.

http://appldnld.apple.com/iPhone4/041-0545.20110325.We3Rt/iPod4,1_4.3.1_8G4_Rest ore.ipsw

Here's the file name:

iPod4,1_4.3.1_8G4_Restore.ipsw

If you look at the file name you'll see that the it tells you what device it's intended for (iPod4,1) and the firmare version _4.3.1_

Once you've download the firmware you open iTunes, plug in your touch, go to the Summary page, shift+click the Restore button and then select the file that you've downloaded.

When is the last time yu did that? When restoring/updating. iTunes contacts apps and verifies that you are using the latest firmware. and will not install an earlier firmware. I do not remember when Apple started this.