I can only offer insights for questions 1) and 3) and all information is based on my own experience.

1)
I've used the seven seas 1400 on gusty, low wind inland lakes extensively as my main foil for all winds from around 8 knots upwards for about 1.5 Years. It was my second foil after my beginner setup and it suited me very well for a long time. I've tried the new version of the seven seas in 1100 and 1300 and found it to be very similar with slightly more glide and less drag. The upgrade not worth the price for me with already owning the 1400.

With that being said, I love the SS1400 for light wind conditions at my 72kg. The stall speed is low enough to get through tacks and jibes quite easily in low winds. You can pump it through lows pretty nicely after some getting used to it (I learned to dockstart this foil, which helped a lot with winging it in light winds as well). I liked the DW210 Stab for light winds. Basically I only stalled if the wind completely dropped or if I made a mistake. Of course a really large pump-style wing would allow you to glide further and fly even slower but i find these super spanny wings no fun for winging. If you can, try the SS1300 before buying it. If you can't, I think it could be a good choice, especially if you can pair it with a long and narrow board for easier takeoffs.

3)
I've used my very high-aspect pump foil (about 1900cm^2 and 1400cm span) for winging a few times in very light winds (7-8 knots) just for the fun of trying it out. Starting it was very easy, i felt as if i could almost start it just by pumping with my legs. There's some guys who even managed to do that on the sabfoil leviathan 1350 on a downwind board with no wing in hand.
Like that:

So based on my experience I'd say that this is not the case, however I have not tried pump-starting a very large medium aspect foil (larger than 1400cm^2) so that might be very easy as well...

Of course faster high-aspect foils (like the f-one eagle) require way more speed to take off and are a different story.

2 foils will be infinitely more fun than forcing a single foil to do all that. You can make anything work, but your body is going to pay for it using a light wind foil in high winds while winging.

I can't answer your questions directly, but I can tell you that having just one foil setup for a huge range is doable ... if you have the skills. My wife uses just one foil, an Armstrong HA680. Before she got this foil, she used two different front wings for light and high wind sessions. She could probably go on the foil in 8 knots with a 6.0 wing, and also use it in 30 knots with a 2.5. With a more downwind-type board and more board volume, a 5.0 should be big enough. But considering the weight difference, that would be a 5.5 for you.
That said, we rarely see 30 knots, and get plenty of days with 12-20 knots, so we rarely go out on days where it's below that. Skill definitely plays a big roll (she's currently working on jumped 360s); there's no way I could live with just one foil. Shims to adjust to different conditions help.

Kind of doable with the help of two different boards. Here in the first two clips I am using the same 850 cm2 front wing. Not claiming 7 knots with a 850 cm2 foil, but with the help of an efficient and properly sized board the low wind range is pretty decent.

95 L board, 850 cm2 front wing, 5.9 m2 wing (partly also with friend's 5.1 m2 wing):



60 L board, 850 cm2 front wing, 3.0 m2 wing:



But once the waves get a bit better I would be slightly overpowered on that front wing, so it makes sense to size down. Here, a 60 L board, 631 cm2 front wing, and 3.0 m2 wing:

Nice! Do you think Flare 1050 is right size for your weight? I see many enjoy 850-950 @ ~70kg. I was considering Flare or X-Glide v2 as a second foil for medium/stronger wind.

Was thinking using smallest pump foil mainly for light wind winging, but dock/flatwater start, SUP would be a nice bonus also.
While I like Takoon moto - affordable gear for everyone (Flare is even so much affordable than other brands equivalents), but I am little concerned about durability, there reports of broken parts, try google search: takoon broken, but some are in French/German. Even on 16th September this year, some guy on Takoon riders fb group posted about broken V2 mast adapter on their new Pump Foil. Carbon and aluminum cause fatigue and galvanic corrosion when in contact, maybe sacrificial anode helps at some extend, do you disassemble foil after every session? have you observed any corrosion in long-term?

F-one is better in this situation, because they use titanium adapter for ALU mast, and overall wings construction seems more efficient especially new generation. Still there are users reports at forums that f-one ALU masts are not stiff enough for large JAM foils. Of course price is also a factor.

I really like the 1050. I've ridden it in 12-30 knots this autumn and liked it all the way through. Of course the 850 would probably even more fun in medium to strong winds but that is the price you pay when you want to have a small quiver. Also I'm riding a normal semi-sinker board (not an efficient dw or midlength board) and appreciate the extra bit of low end I'm getting from the 1050. Most days here in Switzerland we get winds in the 8-18 knots range where the 1050 is great for me. If I had a light wind board or lived on a windier spot, I would have gone smaller.

As for durability, I can't tell you that much. I've seen the reports (I speak german natively and some french) but have not had any problems myself. I'm only on the Takoon gear for about 2 months though. What I can say is:
- The fuselage seems very sturdy and the frontwing connection is rock solid for me.
- After a 2 weeks holiday with riding in salty water every day, there are barely any signs of corrosion. I used tefgel on the screws and disassembled & rinsed everything every third day or so.

My impression with the gear I have from this new generation of Takoon foils is that it's quite well made. It might be a bit behind some high-end brands in terms of weight & aerodynamics but for the price point, I find that really hard to critique. I moved from f-one because of the price difference and so far, I did not regret the move.

I'm sure you'll have fun with both f-one and Takoon.