led cube, strip, transistors

Hello to all!

I am new to this forum and have some questions about the arduino. 1) I want to control my led strip with the pwm of arduino ( have the Mega), the strip is rgb (3A\5m, think is for all 3 colors so 1A\5m per color) with common anode, which transistor would be the best to use, was thinking about the tip31, I want to control just 3m of the strip. 2) second question. I am making an led cube 7x7x7 and would use the Mega to control it. The leds are blue 3,3v 20ma, for controling the layers I think the tip 31 would be fine? But what about the columns, first I thought that I could do it without transistors but then I saw that the maximum current of all arduino i/o is 200ma, so no go. Do you have some recommendations? Do you think that this is ok http://m.instructables.com/id/Self-Contained-7x7x7-LED-Cube/step6/Wiring-Diagrams/ ? He used a npn transistor before the load, is this ok?

Thank you so much. I am not from an english speaking country so sorry for any mistakes.