So normally for sixth forms you can apply to as many as you want, and will usually receive conditional offers (relying on your GCSE grades). I'm pretty sure you don't have to decide which offers to accept, and you will just wait until results day to see which ones you have gotten in to. Then you go and decline the offers you don't want first, and then accept the offer you've chosen. I'm not completely sure about the other questions you've asked, sorry, and I don't want to give you the wrong info. ! Does this help?