[DC Power Supply (5V 10A) - Questions]

There's a simple switching circuit (including LM2576), which has 5V - 3A output.
(the circuit image is attached)
Datasheet: http://www.national.com/ds/LM/LM2576.pdf
Question: Is it possible to increase its current by power transistors?

[DC Power Supply (5V 10A) - Questions]

Thanks, so I can't use a linear voltage regular with this transformer.
as far as I knew, designing a switching (SMPS) circuit is a little hard and needs many parts.
Is there any simple switching circuit to bu used?

[DC Power Supply (5V 10A) - Questions]

Hello,
I'm planning to design a circuit for a DC Motor with these parts:
1* 7805
2 * 2N2955 (paralleling two transistors to increase current)
plus some capacitor and resistors.
(the circuit image is attached)
Here is my question:
If I use a 12volts-6Ampere transformer ( 12V * 6A = 72W), does it provide enough power to have 5V-10A as output?
theoretically: 72W/5V = 14.4Ampere


Thanks,