To not stretch that post out longer, I'll do another.
To address the protein bit, that's untrue and another myth, as the only difference is that plants are not flesh, and thus they do not have the same proportions as it, and thus it won't compare to it.
However, unless you eat just corn or something of the such, you're more than fine.
I can provide a overview of what I eat and how that compares in a day, or what I sometimes feed the kids I babysit if they eat what I eat, and show you how that's so.
Essentially if you want to do it yourself and experiment, go to a site called cronometer.com
It has all the amino acids done out, the essential ones, and all nutrients, simply add in the USDA measurements or similar and it'll have all the nutritional information.

Furthermore, how protein works is you have essentially a pool that circulates around your body of a few hundred grams, which when muscle is broken down it'll re-circulate what it can and reuse it.
Usually you will have 100-300 grams circulating, of all the types of amino acids, mostly the ones you need as it'll mostly be recycled proteins (flesh/muscle), and when you eat more you simply top-off that supply.
Because of this you do not need to even achieve all essential aminos every day, or even every second day, and really won't have a negative impact for weeks till your circulating supply of that amino becomes low, which unless you eat one single food (really a grain) that won't happen.
Beans, potatoes, greens, they're all very well balanced, and honey who eats corn all day (kenya).

B12 was naturally found by us when we drank from dirty creeks and simply lived our daily lives. If you go camping, even if you filter water, you'll get enough b12 from contamination of food or grimy hands.
Because we don't live there most people are b12 deficient. Eating grass fed local buzzword buzzword buzzwords, yes, you'd not have b12 deficiency.
But I don't either, as I can simply rub dirt into my food, or take a pill or injection, which is what I would advise.
Meat only has b12 because of bacteria in the soil they may be eating when munching on grass (ha), you can get that same bacteria isolated without all the bad things of meat for literally less than a cent a day.

As for sugar, it depends, as I eat abnormally high-carb, even for a vegan, I easily get 150g of sugar a day if I eat fruit for breakfast, although I eat a lot, however at the same time I easily get 80-140g of fiber a day, which funnily enough is apparently what scientists found paleo-poop to contain.
Because of that the sugar takes a long time to get into the bloodstream, so there's less spikes, as well as because I don't eat fatty things (essentially anything animal is fatty unless heavily trimmed, oil, etc) typically, blood sugar stays low because nothing is clogging up blood-flow (fat).
My dads a diabetic who doesn't change his meat eating ways and I've used his meter to display the changes, and as long as my fat isn't above about 20% I can literally have 600g of sugar a day and have no blood sugar problems, which is hard to even achieve and isn't the most fun as, well, sometimes you want something warm and potatoes and beans don't have sugar in the strict sense.

I'll take time for anyone if they'll take the time to read it or at least make an argument as even if only 1 in 100 change their mind, that's likely multiple kids who aren't raised with bad foods and every little bit counts.