IPA and unofficial extensions

[Jean-François Colson]

Hello

I have a few questions about the IPA and about its unofficial extensions.

In the consonant charts at 
https://upload.wikimedia.org/wikipedia/commons/f/f5/IPA_chart_2005_png.svg 
there are a few grey symbols which are already in the IPA: ȹȸᴙꞎ.
There are also three symbols I didn’t find:
– palatal lateral fricative (Latin small letter turned y with belt)
– velar lateral fricative (Latin letter small capital l with belt)
– retroflex lateral flap (Latin small letter turned r with long leg and 
retroflex hook)
Is there a proposal including those three letters?

In the suprasegmentals, I found an “extra stress” character.
It looks like a double primary stress ˈˈ. Is that the right way to write 
it? Would a new character be required?

What about the strident diacritic in the diacritics table? Is it right 
to use the tilde below twice (n̰̰ a̰̰) or would a new diacritic (combining 
double tilde below) be proposed?

Voiced bilabial fricative.
Presently, for this letter, the Greek letter β is used. The Latin letter 
ꞵ (U+A7B5 Latin small letter beta) is about to be accepted. Would it be 
used instead of the Greek letter in IPA?

Voiceless uvular fricative.
Presently, for this letter, the Greek letter χ is used. Phonetic letters 
for German dialectology are about to be accepted. I’ve seen in several 
proposals that it includes a Latin small letter stretched x, but several 
code points were proposed for it in several proposals and I don’t know 
where is the last one. Would it be used instead of the Greek letter in 
IPA? The Greek chi has a wavy line while the streched x is very similar 
to and confusable with the standard x.