How to get a new color scheme Qiyi Clock? 

After the spray paint is dry just get a regular paintbrush and make a mark at 12 with any color

Yes

Of course

3h4) For Clock, custom "inserts" (the same shape and size as the traditional paper inserts) are permitted, at the discretion of the WCA Delegate. The inserts must have a clear indication of 12 o'clock that matches the original inserts.

As shown, no. You have to have a clearly marked 12 o'clock to be legal and these do not.