Croon Loc: Naples, FL

Thx for the tips!

Dan' de Bourgogne

Regarding the lens You intend to use, the 24-70/2,8 should be OK. I would take it.
1) First, depending how the room is lit , set ISO...400...800...why not 1600 if required. Don't be afraid...better get a bit noise than no image at all.
2) Then, check the Exposure Comp' on the 5D remains set at "0"
3) Regarding Manual mode: it's fine...as long the room is lit at around "EV5" (metering grey 18% = 1/4 sec; f/2,8; ISO 100), You get 1/60 sec; f/2,8; ISO 1600...or 1/30 sec; f/2,8; ISO 800.
4) Taking photos just under ambiant light (lamps...not day light...no flash):
Set T°K = ca 3800°K /4000°K...if result is too "warm", set less (=3000°K); if "too cold" set more (=5200°K)
With S.S.= 1/30 sec under ambiant light "EV5", to shoot a speaker who stands on a stage in front of a microphone should render correct image as long focal lenght remains "wide enough" (24 mm...35 mm)
If You need to set F.L.=70 mm, set ISO 1600 and S.S. =1/60 sec
So, under ambiant light, either ISO 800-1/30 sec or ISO 1600-1/60 sec depending on focal lenght.
Of course, if the room is better/stronger lit than "EV5", You will set either a quicker S.S. or a narrower aperture or a lower ISO: Your choice.
Now, just my advice...this is what I would do : as long You want to take the pictures only with the ambiant light, set "M" mode...S.S= 1/60 sec, f/2,8 and ISO AUTO (set maxi allowed ISO =1600)!!! It works really fine , just take care to don't frame a bright light source with Your "talent/subject".
5) Taking photos with flash+ambiant: the aim should be to shot 1 or few persons at short distance!
I suppose You don't have an assistant to move around with a flash+soft box...so I suppose You think about "Speedlite ON camera"...
This is probably the hardest job for any photo hobbyist!
a) The shutter speed is still set at 1/30 or 1/60 sec (because You just took few shots under ambiant light)
The ISO used to be set by the camera because ISO AUTO was set. When using flash, ISO AUTO does'nt work anymore: the flash CAN'T set itself to the selected ISO value the camera decided to use.
So, as soon You slide the speedlite on the hotshoe, inhibate ISO AUTO, set ISO 800 on the camera AND on the flash.
Now You get 2 different light sources: the ambiant+the flash.
Depending of YOUR ARTISTIC choice, You can make the "talent/subject" stands out more or less in its environnement.
You can choose to have the ambiant either at the same level as the subject, or at a slightly darker level than the subject or to have the ambiant much darker than the subject.

a) first set the exposure for the "ambiant": You want it set at the same level You had without flash? OK,frame the scene, 1/30 sec; f/2.8, as already done. You want it set at a slightly darker level You had without flash? OK,frame the scene, 1/60 sec; f/2.8 : the scene gets 1 stop darker. You want it set at a much darker level You had without flash? OK,frame the scene, 1/125 sec; f/2.8 : the scene gets 2 stops darker.

b) now You have to add the flash burst: simple!
ISO 800 is already set on the flash...
Set the flash on "TTL" mode.
On the flash head, pull out the white card.
Set the flash head aiming to the ceiling slightly forwards the subject
You are done! Take the shot.
Check the image: Too dark? set "Flash Exposure Comp'" +1. Too bright? set "Flash Exposure Comp'" -1.

c) The color T°K from flash does'nt match with the ambiant?
Yes, ambiant is more yellow and flash is more bluish: this is a recurrent issue.
The unique way to solve it is to put a gélatine 1/4 or 1/2 CTO on the flash and set 5200°K on the camera.
If You dont have a gélatine, simply set "preset flash" (= about 5200°K ?)...the ambiant from lamps will appear quite yellowish, but this is better than a more white "environnement" behind "cold blue frozen" human subjects.

Voilà. Bonne chance

BurghByrd Loc: Pittsburgh

Have you done any research into the subject? A google search for "event photography tutorial" produced the following amoung others. I hope it's useful to you.

https://www.adobe.com/creativecloud/photography/discover/event-photography.html

Dug E Pi

I shoot RAW and Jpg for events. Events may want quick pics for things so the jpg is readyish to deliver and the RAW gives you more leeway to tweak lighting in a fast changing environment.

DirtFarmer Loc: Escaped from the NYC area, back to MA

I don't use Canon so I don't know the capabilities of your camera. If it has dual card slots, set them for backup. The suggestion for raw+jpg is good since it will provide additional backup.