Simply be + to + verb means both HAVE TO, OUGHT TO and BE + VERB + ING.
HAVE TO : It means the person doesn't have any choice than doing it.
OUGHT TO : A suggestion or instruction
BE + VERB + ING : something that you are going to do in the future but it's planned and the day is known.
So be + to + verb are used ONLY in the above scenarios.
Examples
Future:
The train is going to arrive in the station in the next hour
NOW remove "going"
The train is to arrive in the station in the next hour
Command:
You have to complete your assignments
NOW replace "have to" with "are to"
You are to complete your assignments
Suggestion:
You ought to complete your new movie
NOW replace "ought to" with "are to"
You are to complete your new movie
Now for your question. No you can't use (to) because neither the sentences do satisfy the aforesaid scenarios.