All smartphones sold by telcos are warranty by respective manufacturers, so yes they all will enjoy additional year warranty too.
Yes it is dual SIM.
It comes with Quad DAC.
I know all these because I am one of the independent reviewers that received LG G6 in advance and they have shared these info with me, plus the press release also stated the specs which I have published on my blog article:
http://musicphotolife.com/2017/04/lg-g6-singapore-launch-review/
If there are any errors, LG would issue another statement to correct it, hence I take it as final.
Specifications (LG G6 Singapore retail)
Chipset: Qualcomm® Snapdragon™ 821 Processor
Display: 5.7-inch 18:9 QHD+ FullVision Display (2880 x 1440 / 564ppi)
SIM: Dual-SIM (4G/3G)
Memory: 4GB LPDDR4 RAM / 64GB UFS 2.0 ROM / MicroSD (up to 2TB)
Camera: Front 5MP Wide (F2.2 / 100°); Rear Dual: 13MP Wide (F2.4 / 125°) / 13MP Standard OIS 2.0 (F1.8 / 71°)
Battery: 3,300mAh (embedded)
Operating System: Android 7.0 Nougat
Size: 148.9 x 71.9 x 7.9mm
Weight: 163g
Network: LTE-A 3 Band CA
Connectivity: Wi-Fi 802.11 a, b, g, n, ac / Bluetooth 4.2 BLE / NFC / USB Type-C 2.0 (3.1 compatible)
Colors: Astro Black / Ice Platinum / Mystic White
Others: 32-bit Hi-Fi Quad DAC / Water and Dust Resistant / Fingerprint Sensor / UX 6.0 / Dolby Vision™ / HDR10