No 11634, Thursday 25 Feb 2016, Scintillator

As usual I have a lot of unanswered questions when Scintillator appears?

ACROSS
1   Some teachers be lecturesome about famous people (6) CELEBS [T<=]
4   Northern state gets a reduction — that's a blow! (8) UPPERCUT {UPPER}{CUT} (Addendum - {UP}{PER}{CUT} - See comments)
9 Caught entering playfully — Judge ruled out a crime (6) INCEST {IN(-j+c)CEST}
10 Last hurrah from a graceful bird? (4,4) SWAN SONG [CD]
12 Tooth biting in sleep when it is freezing outside (8) PREMOLAR {P{REM}OLAR}
13 An alto could be jarring (6) ATONAL*
15 A crow heading out from a small stream (4) ROOK bROOK
16 Condition I see a lot is dwarfism (10) ATELEIOSIS*
19 Woollen fabrics wrinkled in some regular creases (10) CASSIMERES {In+SoMe+CREASES}* Anno not clear 
20 Reject ingredients of medical drug (4) ACID [T<=]
23 God provided your first branch (6) RAMIFY {RAM}{IF}{Your}
25 No upper-class Incas settled here? (8) SCANSION* Definition not clear (Addendum - ASUNCION* - See comments)
27 Hardly a font applicable to certification (8) NOTARIAL {NOT}{ARIAL}
28 Having false statements on bachelor's, they don't deserve to be looked at (6) UGLIES {UG}{LIES}
29 Placed golf ball around tree, swung and moved unsteadily (8) TEETERED {TEED} around {TREE}*
30 Resolute support that's outwardly cunning (6) STEELY {S{TEE}LY}

DOWN
1   Cheerful carpenter, possibly (7) CHIPPER [DD]
2   Promiscuous hero seduced by crafty clues (9) LECHEROUS {CLUES}* over {HERO}
3   For two times, betray a religious leader (6) BISHOP {BI}{SHOP}
5   Uncle would take that puppet (4) PAWN [CD] [DD] See comments
6   One could be involved in intense workout (8) EINSTEIN {1} in {INTENSE}* Is this supposed to be an &lit?
7   Head of country, Queen to possess this? (5) CROWN {Co...y}{R}{OWN} &lit
8   Switches to somewhat minor bolting horse (7) TOGGLES {TO}{GG}{LESs}
11 Strongholds of religious sects supporting Left (7) CASTLES {CAST{L}ES}
14 Navy is rather depressed (7) FLUENCY Is the only thing I could fit here. Don't know how to classify the clue if it is right (Addendum - BLUEISH [DD] - See comments)
17 Let go of rule when facing coldness after a lot of axe (9) SACRIFICE {SACk}{R}{IF}{ICE}
18 Defence to show off influence (3,5) ?I? FORCE AIR FORCE (Addendum -{AIR} {FORCE} - See comments)
19 Military officer seizes yellow bag and small 7 Dn. (7) CORONET {C{OR}O}{NET} Yellow for gold?
21 Extremely deadly and foul family (7) DYNASTY {De..lY}{NASTY}
22 Honourable man emerging from dark times, say (6) KNIGHT (~night)
24 Leading milliner puts it on 3 Dn.? (5) MITRE {Mi...r}{IT}{RE} Semi&lit

26 Friend, the game ends here! (4) MATE [DD]

GRID