Attempting a catchup...
I love that iconic Dior pic, Enid. There was a whole section dedicated to the photography and it was so visible how much the fashion and the B&W photography enhanced and played off each other. Realised the whole amateur nature of Blogging/Instagram has completely wiped that out why are photographers not crying with outrage 
Anyhow, yes the design of the exhibition was very French dramatic and impressive, a bit traditional in how it's presented (giant walls of text and very chronological) but that's to be expected somewhat.
I have no Duane Reade anecdotes, though surely I must have stepped in one at some point. I remember Walgreen's fondly for whatever reason and Walmart still shocks me every single time for a multitude of reasons but mostly because I could never believe that 'People of Walmart' site was representational for your average Walmart customer it is. I keep flipping back and forth on going to the US, the last time was so utterly depressing as they were clearly still in financial crisis mode when it had passed here and it was really apparent. The Trump win didn't surprise me in that regard, but it has kept me from wanting to visit again, but talk of American pharmacies... hmmm... excellent shelf porn potential there 
Yong, is the Hydrabio you're trying the thermal spray? I'm using that too at the moment, it's surprisingly cheap (I got a 300ml spray for €2.5) with a similar INCI to Serozinc. The nozzle is pretty fun on it too, giant burst (yet not too much water) that instantly covers the entire face, will be relegating it to post workout spray at home as it'll be excellent for that.
Congrats on moving on up, Pupsie! So long so called 'Project Manager'
Interesting on the initial thoughts on TO Vit C 30%. Was someone on here using the Indeed C24 version? I expect it'll be similar to that in consistency and the price point not crazily far apart when taking in consideration offers. Will be curious to know how long it lasts, I know there were complaints about the MAP that's also in a silicone base being used up within a month.
miffy2, is it the Nivea Watery Essence type from JP you're using as I think several have been mentioned at this point?
Skinful, the supposed pH of the Active Formula Vit C is very low, hence it can be a bit much, especially if using Vit C in L-AA form for the first time which is why I think they are a bit cautious with overuse. I think Tsnmummy08 tested the pH for me on it a while back and it was a bit higher than advertised and therefore not as potentially irritating so you should be fine trying it more often, just remember to keep it in the fridge.
Grim, it depends on the kind of Retinol. Prescription strength definitely shouldn't be used with it or alternated, the OTC versions generally less of an issue if alternated but if using a particularly strong one with lots of side effects than the coupling, even if alternated, may put you at a greater risk of over-exfoliation.
Tant, depends on skin type and type of SPF. I tend to go without moisturiser but will stick some form of hydrating toner or serum in between Vit C and SPF.
I'll have to get round to empties some other time but will report on some trials now. See above for the Bioderma Hydrabio thermal water that will be replacing Serozinc for me from now on.
Have also picked up a travel size of the Avene Extremely Gentle Cleanser as I know a few on here like it and the coco glucoside surfactants have promise for keeping the pores clean. I have to say I like it a lot, had looked at it for a Toleriane Dermo alternative but whilst that's an ideal second/AM cleanser the Avene makes for a really good stand alone cleanser, totally non-irritating (on me) and surprisingly good with makeup (minimal) and SPF (lots).
The Daylong SPF has been relegated to the body. It's good and doesn't bother me, applies a bit odd without emulsifiers (it looks to split for a few seconds before rubbing in) but it's just a tad too shiny to wear on its own and I'm not even oily (which it is marketed to), I'll try it with base makeup over it once but on its own it's a bit disco ball, it is good with keeping oil in control though.
I upgraded to the full BR P50, was highly trepidatious and expecting lots of stinging and redness... and nothing... skin seems to get on with it fine 
but it does definitely feel like a step up in terms of texture, am very smooth now and pores are also tackled better with this concentration, brightness is less impressive than with the PIGM version though.
Medik8 CE-Tetra, am really quite enjoying this Vit C derivative and the cosmetic elegance of it, in fact, it sits so nicely on the skin I somewhat forget to finish my routine while faffing about and being distracted. Also, a little goes a very long way. It seems to be doing something, as I don't have the usual instantly noticeable Vit C withdrawal symptoms and skin seems somewhat bouncier and less thirsty. I've been reading into it and it seems to pair well with Retinol, so will have to see how that goes by trying it at night a few times and supposedly really good for sun damaged skin if used with L-AA. SPF efficacy doesn't appear to be diminished either.
I think that's all my experimenting... except, wait, the Akerat 30 has miraculously dissolved two lifetime callouses from daily bike riding within days, for all its immediate efficacy it seems positively gentle everywhere else, Urea is very odd indeed.
I also visited the Dr. Pierre Ricaud shop for their best-selling beaute-test winning neck and decolletage cream. Turns out it's a sister brand to Yves Rocher which made me all wistful and nostalgic as my aunt was always massively conned into buying it and I always got to open the little rolls of paper which were prizes basically GWP with your next order. Did that ever make it to the UK too? Anyhow, the Pierre Ricaud stuff all felt a bit pricey when not on offer, I passed on the neck and decolletage cream as it's kind of bullshit anyhow and the INCI didn't reveal anything interesting but there was a trop chic elderly Parisian grand dame in there with great skin who swore their creams were exactly the same as Sisley. INCI wise in terms of extracts not so much (in fact it's pretty free from plant extracts and essential oils) but the jars do look very similar and they have an identical feel on some. All fragranced so I passed and the price points were high but apparently, it's a bit like the Body Shop/Boden model, constant offers that you have to buy at the right time. They do seem to deliver throughout Europe for free over a low threshold and you get a bunch of freebies with your order. Will have to have a proper browse sometime as a staff member did mention they had fragrance free face creams for sensitive skin, just not in that particular shop.