The pope wears red shoes to remind him (and us) that he has committed his life to God, right down to the shedding of his blood. In the first centuries, the majority of those elected pope knew their reign would be short and end in martyrdom.
As for defacing the ring, EWTN's news director, Raymond Arroyo addressed that very question the other day, on his blog. Here is the explanation.
The destruction of the Papal Ring: Since so many of you are asking, I'll give you a brief rundown. The Ring of the Fisherman represents the Pope's authority and his office. The lead seal of the ring holds a bas relief of St. Peter the Apostle gathering fish from the side of his boat. Above the image is the name of the present Pope--the latest successor of Peter.
In days gone by, the ring was used to seal official papal documents. The image on the ring was impressed upon the wet wax on the back of a letter or envelope. Traditionally people in an audience with the Pope will kiss his ring as a display of affection for the office and the man who occupies it. Once a Pope dies, or in this case, retires, the ring must be destroyed. This is done by the Camerlengo (the chamberlain who runs the day to day affairs of the Church in the Pope's absence). He will go into the papal apartment, deface the seal with a knife and smash it with a mallet. This represents the end of the Pope's authority and his reign. The smashed ring is collected and usually buried with a Pope. This time the ring's remnants will likely be reserved until Benedict, the Pope Emeritus, goes to his reward.
A new ring bearing the next pope's name will be cast and placed on his finger during the inaugural Mass, signifying his supreme authority in the Church. Much more in the days ahead. Stay tuned. Our first World Over broadcast from Rome will be on March 7th. See you then.
The interregnum (period without a pope) and conclave (where the cardinals are literally locked up until they elect a successor) are steeped in tradition and can be quite fascinating. The best coverage will be provided by EWTN (check your local cable/satellite dish provider for the station. There you will gain great insight into how these practices evolved, why cardinals wear red, who governs the church when there is no pontiff and what is happening behind those closed doors. Best of all, coverage is without commercial interruption.
Should you have any other questions, do not hesitate to ask. I will do my best to provide an answer or point you in the right direction.