My replies in purple.
>   (And I'll add the laterals hl, tl, tl';
there seems to be little >or no
>evidence of a separate

I'll comment on sibilants soon when I find the time. However, some
quick comments:
  1. There seems to be little or no evidence of the entire
     lateral series, let alone *dl. Why does one insist on
     laterals in Nostratic, other than to maintain a
     dysfunctional status quo?
Then where did all the Semitic (and Chadic too I think) laterals come from?

  2. Of _course_ there is a "schwa stage" in earlier IE!
     (That is, a stage where schwa existed as a full vowel as
     one finds in NWC languages.) However to claim that a single
     schwa can explain away all the various ablauts existant in
     IE is entirely ridiculous. I'm afraid we need two vowels
     *& and *a, other than syllabic semivowels *i and *u, starting
     at the IndoTyrrhenian stage, to explain the very long
     development of these grammatical curiosities. And again,
     please note Bomhard's specific mention of NWC contacts with
     early IE that can help explain the peculiar centralized
     vowel system. (Have a lookie at my Central Asia map)
I have to agree with the two-vowel system of early PIE (actually four if you count /i/ and /u/).  I think the mention of NWC is to give a parallel example at least, if not to suggest outside influence.  Bomhard did list a number of (possible) IE-NWC cognates.
By the way, by "Indo-Tyrrhenian" do you mean an earlier state of Indo-European including Etruscan or Sumerian or any others, or a wider group of families along the lines of Eurasiatic?