I was afraid of this: that set of stuff is well beyond what I consider appropriate for a forum assist. I don't have enough free time to dig into it - perhaps others will. I will say that you CAN combine many of those checks into a single statement (is coach avialable, do they have a conflict, are they on vacation, etc).

I will add that there are some amazing things you can do (known as gaps and islands problem solutions) to very efficiently check who is available when and do it for all coaches for a large period. Those solutions are NOT trivial however, but you can find stuff online about them (Itzik Ben-Gan is known for these, and I think he has a chapter on it in one of the SQL Server MVP Deep Dives books as well as one of his TSQL books).

Best of luck with it. If someone doesn't step up to spend the time to help you I encourage you to look for professional help.