Expert for twilio programable voice

I have a twilio studio project now and it communicates with db and everything working on this side but 3 things remain. What I 'd like to do: 1st point - music We should add a waiting music for the customer support and when the customer waiting agent 2nd point – Consultant message before enter on the call Actually this is the process - Step 1 : client call the number - Step 2 : he enter the 6 digit code - Step 3 : If the code match our database and consultant is available our system call the consultant. THAT STEP WORK. Issue is at the next step when you system call the consultant. We need to have a message first from your system telling. Hey this is xxx website and you have a consultation, do you accept this. Press 1 for yes or 2 for no. Consultant are called on a phone number. 3rd point - 30 sec before end of the call send a message Each call time are determined at the begining of the call. In fact client buy like 20 package systeme check how many customer buy and its apply at the beggining of the call. But we need to get a function that warn the user 30 before the end of the call and said '' becarefull only 30 seconds left''