Erm did i show you one with 5V 1A?
Not necessary, it may powerup but it may die real fast. These circuits are built with latency of sometimes up to 25% so depending on the components.
Just read the 7805's datasheet. Its max output current only 0.5A so maybe you need to buy a readymade circuit, thses circuits make use of OP-Amps to amplify the current output. The circuit diagrams can actually be found online but its a headache to read.
If you are still not sure, you can go to some of the shops at Sim Lim tower. Some of the shop owners do do circuits for people, just let them know whta you need and bring along what you have.
Eng Hong