I use a square reader for my smart phone. You get one from www.squareup.com. They're really the best option. I mean, paypal makes one now, but their percentages aren't worth it. Plus ew. Paypal.
A webpage is a really good idea, but not exactly required. These days a well-maintained tumblr/facebook page or even a deviantART page can serve most of the same functions. Most people just want a place to go to learn more about you and your drawings. Your average joe con-goer will just want these pages anyway. Social media is fast becoming the brainfood of choice for quick consumption.
The people that are going to want an actual art portfolio website are companies and potential clients. If you are looking for those, it's pretty much mandatory to make a website for you and your art. It doesn't have to be complicated. I know several artists that use wordpress, which is really easy to customize for your needs. All this website needs is a gallery of at least 10 pieces of work, a bio/resume, and a contact information page. Everything else is just extra.
Also important is business cards. They don't have to be fancy, but they are the most important tool to getting people to find you AFTER the con that you'll have. It's much more professional than writing you DA on a scrap of paper, and you'll be giving away 5 for every one person who goes back to look for you when the con is over, but that one person could be the connection you need to get into one of the Big Two, Dark Horse... Disney. They are really an invaluable tool. And as an artist, our business cards are always the coolest! The common choices among AA types are vistaprints.com, overnightprints.com, moo.com (in order of prices. I use moo, but that's because I can have lots of different designs in one order. I use their mini cards) Whatever you do, avoid kinkos/staples whatever your local equivalent is. They are too expensive for what you get. A little planning and ordering ahead is vastly superior to Kinkos!
RE: tables, some cons, especially comicons, give vendors a discount on hotels. If you're not socially shy, once you are accepted as a vendor, look for other solo artists that would be willing to share. Adding even one person will cut your hotel prices in half, and as everyone is looking to save what they can, there are almost always people willing to share. Be nice to your neighbors in the Artist Alley and they can become the people that you do con circuits with in the coming years, sharing gas, hotel and other costs with!
Don't expect to make more than your table costs the first couple cons you go to, especially if you don't have a large body of work to supplement your sales. It will take a while to figure out how to display, whether offering commissions is a good fit for you, how to sell yourself, etc.
Get yourself a black table cloth and either a print book (ilford makes a series that is the most common) or use a tablet/ipad loaded with your work. An easel or two won't go amiss either. Until you have more than 10 prints for sale, you don't need to get fancier than that.
Go to clearbags.com and buy print sleeves in the sizes you are offering your artwork. People are more likely to buy your work if they can get it come safely, and it's pennies per sleeve in cost for you, making it a good deal all around.
Offer your prints in two sizes. You'll be more likely to make a sale if customers have a cheaper choice. I offer both 8.5x11 and 11x17.
Regarding Patreon, it's a great concept. You'll need to be adept with social media AND have a pretty good fanbase (again, pointing out social media) to really make much use out of it. This means getting and maintaining a twitter, tumblr, FB and linkedin page, at the least. AND maintaining a patreon page. I haven't met many non-full-time illustrators able to pull it off without a massive webcomic or other popular project behind them giving them visibility.
If you're into crowdfunding, try instead making a indiegogo/kickstarter for a single project, follow through with that, and use that as the jumping off point for your patreon in the future. Again, you'll have to be adept with social media to get those campaigns off the ground, but it's your best bet!