HOW CAN stock photography's help for an ameteur photographer?

CAN A CLEAR PRINT SIZE OF ABOUT AN A4 SHEET CALLED HI-RES??????

Are most of stock photography websites trust worth?

It could be hi res. Trust. What do you mean exactly. The photographer selling his/her rights to the photograph to these stock places is trusting that the money for the photo is worth the stock company's handling of his/her photograph. So you get out of the image whatever you might put into it. An older artist friend of mine further along in graduate school sometimes uses these stock companies for all they are worth and has come up with some amazing doctored or photoshop images, with merging and morphing and what not. If the photos from these companies has value to you then I trust it would be worth it to you.

The top 4 stock photo sites that I have found are found at: http://www.smilelikeumeanit.com/stock.ht...

I haven't heard of any reason not to trust these sites. There may be others that are more shady.

As for your Hi-Res question. The resolution of an image isn't determined by the size it is printed at. Rather, the resolution is how well the printer can print or how well the camera can capture an image.