Top Tip # 3:
Though I'm trying to sort out the maximum size of signatures. If you come across a signature that is too big, and is taking up all your viewing space, do as follows. Go to a post of the person who has a large signature. At the top right of their signature you will see a little X. Click it, and you will get offered to ignore that persons signatures, or all signatures. Click ignore that person signature, and now the signature will disappear for your viewing of all their past and future posts.
Want to see that signature again? Go to your name at top right, and choose "manage ignore pref". Now you will see that persons name, and a hide button relating to their signature. Click the button and it will say show. Now go and that person's posts and the signature will be viewable again.