Advice on Yale EF-Kit2 set up.

Boohoo

Hello.
I will be trying to fit this wirefree alarm over the weekend but i need some help on where to fit the pir's and door contacts.
1. The alarm has a Home Arm mode where you can have parts of the house armed but you can move about without setting of the alarm.
2. For this option i would like to use at night but the manual to me is not too clear. I would like to have the back/side door and conservatory door to be armed but not the pir's.
3. Also the manual states about the last door entry/exit for setting the alarm but i dont want to have a door sensor on the front door as i was going to put a pir in the hallway.
4. As for fitting a pir in the hallway facing the front door will the post person putting my post through the letterbox set off the pir and then the siren?
5. I have looked at the manual and Yale video's and they seem to be contradicting advice as one manual says fit control/keypad first then extras and siren box but the video says put the siren up first then control/keypad so i don't know what to do and i don't want to do the siren 1st and it keeps going of as i try to install it.
I did do a Paint drawing to insert in this post but it wont let me.

Thanks for any tips you may have for me.