Will using a k & n filter harm my car with the better air flow?

It's for a 2003 Honda Element with awd.

It will do no harm at all. However you may gain a couple more horse power. Which you won't notice.

It will not.

It will also not turn your ride into some firebreathing 911 eating monster, but you should get a nice sticker to put in your window informing everyone that your shoebox on wheels is "K&N equipped".

Because K&N filters use an oiled filtering element, there may be problems in vehicles equipped with mass air flow sensors -- because oil can build up and cause fouling or errors in the sensor which require cleaning.

Other than that, I don't see any problems. But I think what you really want to achieve is get up to 110 mph in your brick, and that isn't happening.

Putting you behind the wheel does the most harm

First of all your vehicle came from the factory with a perfectly good CAI. It's just plastic instead of shiny chrome.
Those cleanable filters have an oil mist on them that migrates to the MAF sensor wires and ruins MAF sensors.
I'd save your money towards a cat-back exhaust system. That's the only thing you can bolt on to your motor to increase the horse power by around 25 hp in your case.

Time for a J35 swap so you can go 110mph in your brick.