6'4 250-330 lbs, currently 300. As a straight beginner all you need is something decent that is big enough to float you that you can get your feet in. Until you have a little practice under your belt you won't know what it is you like and what you dont. If you were 170lbs and wore a 9-10 then you could find people coming out of the woodwork with boards for you to get up on, and progress through and try out untill you knew what you like. You could also find proshops willing to let you demo a bunch of boards once you have a little bit of skill under your belt to find the right one. When the boards and bindings are all special order they don't usually give you that same opportunity.
I had a hard time finding bindings I could get my feet in easily, most shops had 1 or 2 of the big bindings at most and if they don't fit they can order you something. The Liquid Force bindings seem to easily run 1 whole size small and I had trouble getting in and out of the Hyperlite bindings. I find too find that the Ronix bindings run true to size and the CWB bindings were big enough to get my feet into but since I have smallish ankles for a big guy I always had way too much lace left over. I switched to closed toe bindings primarily because I didn't like the laces wrapping around my toes.
Everyones foot is different so try to find something you can try on. I like the Ronix Parks or the precursor the Relic, I have one of each and I love them. For closed toes I also liked the CWB Marius and for open toes I did like the CWB Vapor and the CWB Torq bindings since they had the hinge that allowed easy access. Although with the hinging backs on open toes you only have the glue/stitching on the 6" section on each side of your foot holding you in and I destroyed a pair in about a year. I initially went with the CWB bindings because that is what I could find a 2xl in stock in local shops that I could get my foot in since they had those hinging backs. Once I found Ronix bindings in my size while traveling I was hooked.
The downside of being a big guy is you are buying a board that is pretty much only for you to use and you are pretty much buying your way through demos. If you have a good local pro shop they might be willing to order you a board in to demo and let you swap it out if it doesn't work for you, perhaps for a modest cost. If you don't live close enough to a big retailer or pro shop to try on some bindings but you are planning on spending 3-500 on a pair site unseen then maybe it would be worthwhile to take a trip somewhere you can try on. I know Boardco has a local store (its M&M Watersports in Springville, UT who operates boardco) but I couldn't tell you if they have full access to all the inventory there. If you have a reason to be in Orlando Performance (http://www.perfski.com/
) has a huge inventory and I have ordered a ton of stuff from Evo (http://www.evo.com/
) if you had a reason to be in Seattle they have a store. Otherwise ordering something Ronix in the 2xl (13-14) might be your best bet but you will have to guess how much flex/stiffness you want. If you go closed toe they pretty much go Parks, Frank, One, Code 55 from most flex to most support.
They have you pretty much hooked up on boards, anything 145 or bigger should work. I ride the Liquid Force Super Trip 147 now, I bought a second one so I have a backup, and I went with the hybrid because I ride cable a handful of times a year. I originally bought it (site unseen) just to be my cable board but after trying it I switched to it for my everything board. I have tried dozens of boards to get to the point I am at now where I have a pretty good idea of what I like. For your first board I would look for the best deal on something used or closeout and probably lean toward something beginner from one of the major manufacturers, Ronix, Liquid Force, Hyperlite, Obrien, CWB, maybe Slingshot from the last 2 - 3 years. You usually don't have to worry about the bindings unless you find one of the weird boards or start to get older than that since they are pretty much interchangeable the only thing you might have to do is swap out 1/4" screws for M6 screws or vice versa. Try to avoid the cheap off brand boards from Dicks or Sports Authority or the like.