Second the recommendation of Hypertherm, the 45XP will pierce up to 1/2". A 65 gets piercing up to 5/8", an 85 increases it further. Piercing is what most of the cuts are going to require. Bought with the machine torches, they come with the needed round 14 pin cnc interface connection. If memory serves me here, I think there are 7 connections you need to feed to the THC coming out the connector on the power supply, one of those being a ground. Having just finished my build, some of that stuff is fresh I'm my memory. I went with a TMC3in1 THC board with the required ESS smooth stepper board plus an expansion board to give me more connections. And of course I used Mach4 for the control of both boards and the post for SheetCam.
Warp9 has all those mentioned. Don't even consider Mach3, those pieces just won't work well with it.
I'd recommend going with the expansion board as the limit switch connections on the THC board are real limited for that purpose. You'll need limit and home switches as well as a probe input. Mine has all those. The CNC4PC's
C25S is the only expansion board I'm aware that fits the other two boards. You can purchase all 3 boards as a combo from CNC4PC, but you'll have to go to Warp9 for the plugins, screen set and other software pieces. Warp9 is the official support for the THC and their control board the ESS.
If your table is going to be a full size table, I'd recommend staying away from simple stepper motors to drive it. You need speed above most all else. I used hybrid steppers on all four drives, ball screw on Z and rack and pinion on X and the 2 Y drives, reduced via timing belts for the rack and pinions. I've tested mine at rapids up to 1500 ipm on X and Y, but they're now set at 800 ipm rapids. You'll most likely never see that kind of speed on Z, mine is now set at 300 ipm or 350 ipm, don't recall exactly this morning. I cut thin sheet up over 300 ipm. At those feed rates and the rapids that occur, make dang sure you use keys on the pulleys attached to the motors. Don't rely on set screws alone. Not a big deal on the Z motor, just use a quality coupler there to the ball screw. I direct drive that.
I designed my table over a couple month period, shopping for the pieces I decided to buy and designing around them. They came from a large variety of vendors, I never found a single source for all of them. But I machined a large amount of the parts. Hate to think of the cost without me doing that. I've heard numbers tossed around out there on what people spent, some of those might have been better off just buying the whole thing they were that close to prices I see on the web. My build was under 5 grand, probably hovering around a tad over 4 grand not including the plasma unit as I had that already. Nearly a grand of that was the machine torch and consumables I bought, I had a hand held torch originally. Don't make my mistake there and just get the machine torch right out of the gate. I paid to have my first set of slats sheared too and had them bend me up a pair of Y rail covers to keep the crap off the v rails, that wasn't cheap.
Hope that helps ya along with your build. Oh, one other thing, you want the floating torch mount. Start out knowing that, the break away mount, meh, might be more trouble than it's worth. I don't have a break away. I program my starts and stops to avoid tip ups. That's worked so far. Plus I lift the torch maybe a bit higher in between to avoid any as well.
The mention of a drill on the machine is a good one. I did consider that, but in the end I abandoned it. I have a punch press so use that for small holes. I was going to use one drill size or a spot drill for everything, mount a straight drill body and use a relay to turn it on and off. I got tired of designing and wanted to get to building, but did consider a drill that fit in place of the torch for that. Never found that particular drill. Now I can see a spot drill wouldn't work out that well as the height of the slats is a continual moving target. But a pilot drill would.
One thing that would be handy and is on my to do list is laser led light cross hairs for the center of the torch you can turn on and off to indicate to set the torch to your material corner. I didn't consider that until my torch mount was designed and machined. May make another mount to incorporate those.