First off all take a breath and do one thing at a time mate, your shed if you plan for 15 pigeons personally I would have 20 perches. You can make box perches if you like or even just use the plastic v perches pretty cost effective and quick to get you small shed ready for young birds. Once you get your young birds in there they will trap to anything mate just get the pigeons into a routine and stick to it then you can adjust the feeding if you need more control off the pigeons. You will get racing youngbirds this year but just worry about getting your loft ready and getting some pigeons in it first off all. After the season then look to what's the plan for next