Further questions about typing Windows logo

Tl;DR at the bottom, correlated with the failed superscript notations in the body of my novel (I don't know BBcode; I just know how to follow instructions--but apparently not well). Just a little overexcited and wordy cuz I'm a nerd.
I wanted to reply to this thread, which I guess would have irritated people, but luckily for social conventions, it's archived or locked or whatever. The answers in that thread provoked more questions.

I was pretty excited about dafont.com when I discovered it in this thread, and particularly about the font linked since I came across the thread when I was asking the same question OP had asked. But then I realized that for other people to see things displayed as intended, they would also need to have that nonstandard font installed, right? ¹
And based on other research not from this forum, it looks like even Wingdings rendered in browsers on Windows computers often displays as some default font, although it looks like there is a way to add extra code to "force" browsers to display fonts they might otherwise ignore.
So if custom fonts have the limitation I guessed above, then typing ÿ in Wingdings (copied and pasted in Calibri so that people whose browsers can display the Wingdings character as intended would still see the "normal" character) seems to be the best way to get the recipient to actually see the icon when sending messages. ²
However, pasting the Wingdings character into Facebook made it appear (even in the text box, before sending) as an odd rectangle with F, O, F, and F sort of where the four window panes would be, so that's not particularly helpful. Copying that character from a sent message back into Word gives me a rectangle (that I assume is the same one you get if you use ctrl+backspace in most places that don't use that keyboard shortcut to delete an entire word). Is there a simple fix for this? ³

1. ^ If I download a font from dafont.com and use it (primarily for IM), characters will not be displayed in that font for people viewing that text on other machines without that font installed?
2. ^ Is the easiest partial solution for the largest number of operating systems/software/etc. to display a window icon just to use ÿ in Wingdings font?
3. ^ The way I'm implementing that solution now, it's not a solution for Facebook. Is there another step I can take to make it work for Facebook, even with some more complication (maybe using that character with HTML or BBcode or something)?

Thanks to anyone who can shed light on any of this!