Iphone 4s simulator problem ?

I was trying to run my unity game on iPhone 4s simulator using Xcode to produce some screen shots for iTunes connect.

There are several problems I encountered on the way and tons of confusion hoping someone might shine some light here.

I have tried all other simulators (iPads, iPhones) and never had any problems.

1. When I select simulator SDK in the player setting i notice that "architecture" field is greyed out and changed from "Universal" to "x86_64"

2. When I open Xcode I can't select iPhone 4s as a simulator to run this build on. In order to be able to I have to go to "Build settings" -> "Architectures" -> "Architectures" and change from "x86_64" to "Standard architectures i386 x86_64". After this change iPhone 4s it is now available as a simulator choice.

3. Xcode builds without errors but as soon as I start the app on the simulator it fails, it won't even get to unity logo.

dyld: Symbol not found: __ZN14Il2CppIUnknown3IIDE Referenced from: /Users/user/Library/Developer/CoreSimulator/Devices/FFABF00E-A414-495A-8FF6-8AF50B97343C/data/Containers/Bundle/Application/FB0C2EB1-3581-4061-BBC5-98F09F395218/myapp.app/myapp Expected in: flat namespace in /Users/user/Library/Developer/CoreSimulator/Devices/FFABF00E-A414-495A-8FF6-8AF50B97343C/data/Containers/Bundle/Application/FB0C2EB1-3581-4061-BBC5-98F09F395218/myapp.app/myapp

I have reproduced this exact same error with an empty unity app.

Here are the questions I hope you could answer:

1.Is this the proper way to simulate iPhone 4s ? If not how should I go about it ?

2.Is there some problem a novice developer doesn't know regarding those different architectures ?

3.Considering that when "Device SDK" is chosen in player setting, architecture is "Universal" (in unity editor) can I expect this app to work on the actual device ?

Unity 5.3.4f1 Xcode 7.2

any help appreciated, thanks.