Make a USB charge point from DC input

[Vindhyachal.takniki]

I have to make dc charge input from two options below, so that any mobile or related device can be charged:
1. Input: 17.5V-29.4Vdc
   Output : 5V/1A for USB charging
   Led: Led indication when mobile is plugged in i.e charging occurring
        Led off when charging completes or nothing is plugged in
   
2. Input: 7.5V-12.6Vdc
   Output : 5V/500mA for USB charging 
   Led: Led indication when mobile is plugged in i.e charging occurring
        Led off when charging completes or nothing is plugged in 
       
Since I need low cost option, so I am planning to use LM2576 option for both of them.
Lowest I think would be LM7805, but it gets heated up evn in case of 12.6V & 500mA option also. Since it produces wattage of around :
(12.6V-5V)*0.5 = 2.55W
So I am not using this.


1. Is there any other low cost solution which can be used, in which inductor is not be used externally. Dont want to use it since not availble in low cost option in local market.
2. I also want to limit the current to 500mA & 1A so that any device should not be able to draw more current. What should I do in this case? What is recommended use for this. Or let the load draw more current in case of error/overload, LM2576 will thermal shutdown in case of over-temperature.
3. Led indication when charging happens i.e when current is flowing. Should I place a current sense & place a op-amp across it & make a led glow or any other option also available?