>>Just wondering if (judging by my facial features - see pix) I'd be able to pull off a believable crossplay at a con this year.
Yes. Yes you will. If you are concerned about your facial features, I would suggest some simple highlights and lowlights to sharpen the features of your face. I can tell you are a girl from your pictures (cute too ^^), but I can see you easily making some great bishonen characters. Lucky you, you’ve got a face that can go well either way with the right makeup, so bishonen looks are well within your grasp.
>>I'd like some advice on what characters would be good for me to crossplay as to fit my features.
As a fellow newbie, the best advice I ever received is don’t worry about what you fit; think about what fits you! Liking a character is far, far more important than looking like one will ever be. Enjoying costuming a character that you like will take you much further, because it will keep your interest.
>>The hat? Maybe. Everytime I wear one I get mistaken for a guy. Don't know how with my shapely body though.
The right wig or hairstyle will have the same effect as the hat. ^^ If you’re worried about your curves, take a look at http://forums.cosplay.com/showthread.php?t=27238
which both have great advice from all the local lady crossplayers about hiding / reducing feminine curves.
If you have a specific problem you are looking for assistance with, go ahead and ask! This is a wonderfully supportive community, chock full of great ideas, and talented costumers.
Good luck, and let us know which character you decide on cosplaying!