Hola Garry

These verbs all have different meanings (except for ser and estar that are both "to be" but used in different scenarios in Spanish). 

"... y esta noche va a haber una cena..." 

This is "there's going to be..." not "it's going to be..."

Then, for:

"...la decoración va a ser muy elegante y el menú va a ser muy variado" 

you need "ser" because this is saying "is going to be" not "there's going to be..."

Again, the last one needs haber:

"...va a haber música" 

there's going to be...

Remember, if the word "there..." is there, you will need haber. 

If you remember well, you have this in all tenses with haber:

There is / there are = hay

There was = había or hubo

There will be = habrá

There is going to be =  va a haber

Have a look here so you can see haber (impersonal haber) it in all tenses.

I hope this clarified it.

Saludos

Inma