Hello NDekens welcome to the site. Lots of good information here. I see your from Sacramento. I am just up the road from you in grass valley near Beale AFB. I have had a ranch kettle for a few years now and done both large and small cooks.
For the amount of charcoal and temperature for reaching 350 at least from my experience is 2 full Weber chimney of lit coals and that should maintain that temp for a little over an hour with two bottom vents wide open one closed. Of
Course it also depends on how much food you are cooking as well.
I’ve grilled two pork chops for the wife and I on the ranch and just used the mini Weber chimney for that cook. I have done a ton of tri tips on it for the guys at work. Typically I’ll do one chimney of lit on top of another chimney of unlit banked to one side with fire bricks. I can cook up to 12 no problem at 275 and have coals left after an hour and a half or so.
Ribs are nice on the ranch two. I have done up to six racks flat with no problem similar to the tri tip arrangement with a little tweak two chimney unlit, bank to one side held with fire bricks, pull 12-16 out of the center and return those lit. Maintain 275 for about 5 hours not problem for racks.
I have only smoked a 250 on the ranch once. Decided on the fuse method for that where I lined half the ranch edge with 3 stacked high briquettes and lit one end. Wasn’t real impressed and had a hard time holding 250. Went 9 hours but I didn’t really care for that method. Maybe it was my technique.
Anyway, you may be surprised how little or how much charcoal the big fella uses. It all really depends on how you use it. For me I think grilling direct like hamburgers and hot dogs burns up the most since you are using mote surface area. low and slow uses a lot less charcoal. Let’s know if you end up with a ranch. Again welcome to the site. Look forward to hearing about your cooks in the future
Dustin