Electrical – Should I be switching just the hot, or both hot and neutral

I'm thinking of building my own alarm clock because none of the one's I've found are meeting my needs, and because it's kind of fun. I am a bit out of my depth on at least on part though, and I want to make certain I don't do something unsafe. I'm not sure whether or not I can use a common neutral line for two circuits. There are two diagrams I'll try to attach to this post that should explain the two options I'm looking at. Finding double-pole switches is a little more difficult than single-pole, and a bit more wiring (not much of a problem for wiring though).

I'm kind of worried about a neutral line being shared because if one alarm device is activated, all the neutral returns will be 'returning' (for lack of certainty of a term to use). Since multiple devices could (and probably would in some circumstances) be plugged in to outlets that have 'returning' neutral lines and share a common but unheated hot line. Might the current be driven backwards through a device in this scenario (ie, Each Switch Controls Only Hot, Timer-less Feed Open, Timer 2 Open, Timer 1 Closed, Circuit 1 fed by Timer 1, Circuit 2 fed by timer 2).

Is there a great danger in having a store-bought wall timer plugged in but with the neutral and possible sometimes the hot wire both 'returning' and hot due to the devices they're connected to receiving power from the other timer or from the timerless-activation switch?

Also, is there something I missed with my design in terms of safety or functionality (or sanity)?

Is there such thing as an anti-backflow device for AC? Or for DC for that matter?

Explanation of the system:

1. I want an alarm to go off with a bright light and a loud noise and maybe a strobe light and whatever else I might want to add later.

This is what Timer 1 is for. The night before I will set Timer 1 to the desired time, and will set Circuits 1 and 2 to be fed by Timer 1.

2. I want to be able to turn off the bright light and loud noise while still leaving enough light to see.

The loud obnoxious items will be set to Circuit 1. The USB light will be set to Circuit 2. When the alarm goes off, I will make my way across by bedroom to quickly switch Circuit 1's feed from Timer 1 to Timer 2. Since Timer 2 is neither on nor is the switch for Timer 2 connected to bother Circuit 1 and Circuit 2 at the same time (… unlike a previous design iteration…), Circuit 1 will no longer be being fed power, and thus the obnoxious items will stop making me want to perform ungodly acts of destruction upon them.

3. I then want to take medication set near the system the night before. I will then set Circuit 2 to be fed by Timer 2 instead of Timer 1, thus deactivating the USB light.

4. I may want to add in a device outside of these circuits (like how the projector alarm clock and Wall-to-USB adaptor are wired in) that allows me to turn on a light for 30 seconds or a couple minutes until I'm back in safely bed (stubbed toes hurt). I might use the kind of timer you see in some bathrooms that activate a heat lamp or a fan by turning the knob to the desired amount of time, after which the lamp or fan turn off.

5. I then want to go back to sleep until some time I'd set the night before (maybe half an hour later, maybe 5 hours, whatever).

This is what the second timer is for. Circuits 1 and 2 will have been set to be fed by Timer 2 when I got up for Timer 1, and so when timer 2 goes off, so does the alarm again.

6. I want to be able to test the alarms before I go to bed without having to switch the timers themselves to "Always On" and then back to "Timer" mode.

This is what the Momentary-On switch before each timer is for (I press it and it closes the circuit as though the timer had gone off).

QUESTION: If I press the Momentary-On switch, creating a bypass with near-zero resistance, would this de-power my timer? I suspect yes. Also, if the timer were on and I press the Momentary-On switch, would this wind up with insufficient power through the timer, quite possibly buggering it up? I hope not but suspect yes…

7. I want to be able to activate the items throughout the day without having to turn on the timers.

This is accomplished by a switch.

8. I don't want to light anyone or anything on fire, nor do I want to electrocute them, unless they're reeeeeally really annoying me.

9. I'm trying to make this portable (although I suppose that term means different things to different people). I'm not certain in what to place the switches I buy (probably not light switches, more like the kind of switches you see on, for example, a coffee maker), but I've found a wooden box from Dollarama that might make a good thing to use for a first try, since I have no idea what else to use. Any ideas? I seem to remember/remember reading of controls being placed in wood back in the day?

Location: Alberta, Canada