I've been looking up for a list as well but couldn't find one, so I have compiled this list of instruments.
The list is grouped the same way as it is in Notion 6 when you setup your score.
The ones marked with an (*) are not included by default, and can be purchased separately in various bundles:

https://shop.presonus.com/Notion-Expansion-Bundles

Disclaimer: this is not an official list. I've done my best to ensure it is as complete as possible, but there is no guarantee I haven't made any mistakes.

Re articulations and techniques there are heaps of them, but I haven't had the time (or courage) to compile a list.


Instrument List

Basic:
-----
NTempo
Treble Clef Staff
Bass Clef Staff
Acoustic Guitar
Piano

Strings:
-------
Violin I (section)
Violin II (section)
Viola (section)
Cello (section)
Double-bass (section)
Violin (solo)
Viola (solo)
Cello (solo)
Double-bass (solo)

Woodwinds:
---------
Piccolo
Flute
(*) Alto Flute
(*) Bass Flute
(*) Flute Section
(*) Flute Duo
Oboe
(*) Oboe Duo
Cor Anglais
(*) Oboe d'Amore
(*) Bass Oboe
Clarinet
(*) Clarinet Section
(*) Clarinet Duo
Bass Clarinet
(*) Contrabass Clarinet
(*) Basset Horn
Bassoon
(*) Bassoon Duo
Eb Clarinet
Contrabassoon
(*) Clarinet (jazz)

Saxophones:
----------
(*) Sopranino Sax (orch.)
(*) Soprano Sax (orch.)
Alto Sax (orch.)
Tenor Sax (orch.)
Bari. Sax (orch.)
Bass Sax (orch.)
(*) Contrabass Sax (orch.)
(*) Soprano Sax (jazz)
(*) Alto Sax (jazz)
(*) Tenor Sax (jazz)
(*) Bari. Sax (jazz)

Brass:
-----
Horn
Trumpet
(*) Piccolo Trumpet
(*) Cornet
(*) Flugelhorn
(*) Soprano Trumpet
(*) Bass Trumpet
Trombone
Bass Trombone
(*) Alto Trombone
(*) Trumpet 1 (jazz)
(*) Trumpet 2 (jazz)
Euphonium
(*) Horn Section
(*) Trumpet Section
(*) Trombone Section
Tuba
(*) Wagner Tuba
(*) Trombone (jazz)
(*) Bass Trombone (jazz)

Guitars/Basses:
--------------
Electric Guitar
Electric Guitar (7 string)
Electric Bass
Electric Bass (5 string)
Electric Bass (6 string)
Upright Bass
Acoustic Guitar
(*) Classical Guitar
(*) Banjo
(*) Mandolin
(*) Ukulele

Keyboards/Harp:
--------------
Piano
Clavinet
Electric Piano
Techno Synth
Harp
Celeste
Harpsichord
Organ Manuals
Organ Pedals

Drums/Cymbals:
-------------
Drum Set
Bass Drum
(*) Bodhran
(*) Bongos
Concert Toms
(*) Long Drum
(*) Piccolo Snare
Snare Drum
(*) Side Drum
(*) Tenor Drum
(*) Chinese Cymbals (Bo)
Crash Cymbals (orchestral)
(*) Finger Cymbals
(*) Sizzle Cymbal
(*) Splash Cymbal
Suspended Cymbal

Pitched Percussion:
------------------
(*) Almglocken
Crotales
Glockenspiel
(*) Handbells
Marimba
Roto Toms
(*) Saw
Temple Blocks
Timpani
Tubular Bells
(*) Tuned Gongs
Vibraphone
(*) Whistling
(*) Wine Glasses
Xylophone

Other Percussion:
----------------
(*) Agogo
(*) Anvil
(*) Bell Tree
(*) Brake Drum
Cabasa
Castanets
Caxixi
Claves
Cowbell
(*) Cuica
(*) Drum Sticks
(*) Flexatone
Ganza
Gong
Guiro
(*) Log Drum
Maracas
(*) Ocean Drum
(*) Rainstick
(*) Ratchet
(*) Sand Blocks
Sleigh Bells
(*) Slide Whistle
Tam-tam
Tambourine
Triangle
(*) Vibrastick
(*) Vibraslap
(*) Water Gong
Wood Block

Sound Effects:
-------------
(*) Car Horn
(*) Champagne Bottle
(*) Church Bell
(*) Cuckoo
(*) Duck Call
(*) Flower pots
(*) Hammer
(*) Handclap
(*) Lead Pipe
(*) Lion's Roar
(*) Nightingale Whistle
(*) Referee Whistle
(*) Siren
(*) Siren Whistle
(*) Thunder Sheet
(*) Train Whistle
(*) Wind Machine
(*) Whip

Vocal:
-----
Voice
Soprano chorus
Alto chorus
Tenor chorus
Bass chorus