Seeking Advanced Help

So I'm about to go aero and right now I got enough for my veg room to be complete but I have some questions that I can't find answers for.

Do I need to have a 24/7 nutrient monitor for each or my rez if I have a ppm/ec/tds pen?

What's the best way to veg plants without a lot of power usage? Currently using a 1k super mh hortilhx and I would like to add more to flower and have less for veg without sacrificing yield/growth.

How much space per plant in aero does each need to become big and shrugged?

Would individual buckets for each plant be better than 2-3 per tub?

Do you need a co2 sensor or gauge to measure ppm in the air if using a CAP propane co2 generator?

Please help ty for the help in advance +rep

My aero sprayer tubes are doing just fine without constant monitor- I just check ph/ppms daily just as I used to when I was doing DWC using pen and/or ph testkit but yeah things do happen fast in aero so I see how a monitor could help. I think 18/6 is your best bet for a veg light cycle- I'm going 24 hrs continuous now but my power bill is getting ridiculous.
Not sure I can answer your other Qs with any accuracy because I'm new to this as well but here's my 2 cents. I managed to squeeze 8 2" netpots in a 36" square tent but only using 4 ATM- my 4" dia tubes are only 24" long so they are 6" apart- thinking that may be too close unless you plan to keep them small like me. If you are using buckets keep in mind the roots in aero will not get huge like in DWC- you might be able to squeeze more plants than you think in those buckets depending upon how big you want them to be. Hoping somebody else more experienced in aero will chime in

T5's are great for rooting/veg. Cheaper than a 1000w for sure. No need for a perpetual monitor. If you have a meter, try and check every other day - Watch your pH and PPMS. Keep it around 5.8. Letting the bucket scale through the week is beneficial. Drop it to like 5.5 and then res change when she hits 6.3ish....Regular res changes. At least once every 7 days or so. Seperate tubs is necesarry for optimal growth, or they'll be competing for root space. More space for the roots the better. I would do my best to dial in everything else before worrying about C02.

HO T5's are what I use for veg. Great so far with very little stretch, at 54 watts each there is substantial power savings.

advanced led 240w full spectrum grow lights.. i have them.. and um... it dont get any better ..

Wouldn't worry about the CO2 ppm's. In my experience spending the money on the monitor will likely lead to running your generator all the time. I would just put it on a timer myself.