The redness on your arms sounds like it could be a condition called Keratosis Pilaris Rubra, which is really common (most poeple who have it get it on their face :| ), and while I agree that it's not the most beautiful sight in the world (I have straightforward KP), I've come to realise that it doesn't seem to bother anyone other than me. As for you being a size 12, I asked around (for the sake of this thread) and every guy I asked said he'd prefer a size 12 girl to a size 8 one. However, if you want to lose weight and tone up then no one is going to think of you as shallow for wanting to do so. Start out easy, maybe give up something like chocolate for Lent (the next 40 days) and carry on if you want to afterwards.