Marvin, congratulations on your new enlarger, and welcome to APUG.
If you search the eBay camera and photo category every day or two for the search string "Beseler carrier," you will see all sorts of Beseler negative carriers and the one that you want will come along eventually, if you can be patient. If I were you, I wouldn't pay full price for a new one.
Yes, you will want to have a lensboard for each lens that you use. Fortunately, the lensboards are very common and you will have no problem picking them up on eBay. You might need to pick up a 39mm retaining ring for each lens, but those are extremely cheap.
If there is any chance that you will purchase a 6x7 or 6x9 camera, you might want to buy a 105mm lens instead of an 80, or in addition to the 80. Your enlarger will handle negatives up to 6x9, which is one of the reasons why I think that you made an excellent choice. Some medium format enlargers only go up to 6x6 or 6x7. I think you will find that 6x9 folders can be a lot of fun, and there are also the excellent Fuji 6x9 rangefinders to consider.
Lastly, my advice is to use a sniping system on eBay if you aren't already; it will save you money in the long run. I can recommend
www.auctionsniper.com, and use that site myself for all my eBay bidding. Bidding early on an eBay auction only signals your interest to others and allows them to bid higher in response. Don't signal your interest in any eBay item, and always bid your maximum bid in the last 5 seconds of the auction.
Be sure to let us know how you get along with your new enlarger!