You must be kidding me, noone will mind at all. Your art speaks for you more than enough. In terms of conventions, everyone has given more experienced comic-con advice. Always have some lower priced items on your table. More pricier books and prints is fine, but as a con go-er I know I don't always have the cash left every con but I still want to pick something up. Also, if indycon is anything like the cons I've been to, a decent run of business cards may do you some good. Something that stands out. Cons can get pretty busy, some people are more than happy to pick up your card even if they can't buy anything at that moment. You may not have made a sale, but you got your art and name somewhere in their pocket and there's a chance they'll stumble on that card again and check your stuff later.
If you're taking a sketchbook to the con, avoid drawing and staring at it aha. It may be tempting, and fun but looking like your really engrossed and busy might put some people off from approaching you. They might watch but they may feel like they don't want to 'disturb' you and so don't strike up a conversation. Smile, compliment people and their outfits. Get an atmosphere going around your table.
Hoenstly I don't think you have anything to worry about. If I wasn't a Londoner I'd be all over that com looking for some physicals of BENEFACTORS ! I can't wait to see more of it. <3 Let us know how the con goes.