Georg Seifert

I wonder if the "national preference" for certain accents is caused by the preference for certain typefaces that happen to have certain accents and users get used to the style of that typeface?

If you need two or three masters on the weight axis depends on the design of the font. So you can try to us only two, interpolate the instances and see if you like the result. If not, you add add the Regular in the middle. If you need corrections only on some glyphs, you can add add extra 'masters' per glyph (in Glyphs.app with a brace layer and with an extra UFO in designspace files, I believe). That way you save a lot work. 

You can draw the serifs like this to prevent this:

The problem is that there is not one Windows Cleartype. The result looks a bit different in each browser. So you need to check each browser/app in a real environment and even on different versions of Windows. 

Adrien Tétar said:

Why would one manually decompose components before exporting fonts?

because you might need do remove overlaps. And for CFF it doesn’t make a difference. For TrueType it would be bad (to remove all).