User Manual Vizio E24-C1 E Series 65-Inch Class 1080p 240Hz Full-Array LED Smart TV

I hooked it up to a 1080 x 1920 video card in my desktop with
an HDMI cable and the text looked fuzzy. Found a menu setting
under Picture for "Computer" - set it to that and exited the
menu and the text is now crisp and clear.

You can connect as many speakers as your amplifier can drive.
The TV does not serve as an amplifier for external speakers.

Yes it has a built in Digital TV Tuner but you will need a
Digital capable TV antenna. I get 46 over the air TV
Channels Half of them in full 1080P HD. I use this in my RV
with the batwing it came with on the roof (with antenna
booster)

This TV has a great media and video player that will read and
play from a USB Flashdrive but there is no way to hook up any
blue tooth devices such as headphones or your cell phone.

It will work without internet but as a regular TV you'll have
to get cable services, all smart TV's need Internet to use the
features as Netflix, Amazon and all. So if you want this TV
to connect it to your cable service and watch regular tv is
fine but to watch YouTube Or Netflix you'll need Internet
connection

No it does not come with any cables

Yes it has a headphone output not sure what the speaker
wattage is . I have a 2000 watt sound system hooked up to it
and it works just fine.