ok, since someone asked for info about catherine as a child and since we do need a subject change...
catherine is the daughter of lorenzo of medici and madeleinde de la tour d'auvergne, who was a countess of boulogne (daughter of jean 3rd de la tour and jeanne de bourbon-vendome - royal blood). she wasn't a complete merchant then

. the marriage was actually proposed by francis 1st who wanted to become friends with the pope of the time, leon 10th who was the son of lorenzo the magnificent (a medici himself). francis wanted to invade naples, he needed some sort of consent from leon and tried to bribe him with an amazing marriage for his nephew...
madeleine and lorenzo had an amazing wedding courtesy of francis 1st. the wedding was around the same time as the baptism of the dauphin (francis) and lorenzo was the representative of the pope at that particular event.
a few months after the marriage, lorenzo got really ill and was sent to villa sasetti. a few other months later (13 april 1519) catherine was born (baptised caterina maria romula). her mother died 15 days later and 5 more days later her father died. as a result of their deaths the pope broke the relation to the french king and got closer to emperror charles. catherine was taken to rome by her grandmother, alfonsina orsini (mother of her father) and her cousin giulio de medici who was administring florence after her father's death. francis claimed catherine to raise her himself but the pope refused because he was planning to marry her to ipolito de medici who was the bastard son of giuliano, duke of nemours. also because the pope planned to break the french alliance...
catherine's cousin, giulio de medici was elected pope in 1523 and took the name clement 7th. (the guy who refused henry 8th divorce...). because he was elected pope, the official head of the family became ippolito, catherine's bethrothed (not officially but still...). he was 13 years old. catherine and the bastard son of giulio, alessandro, moved to poggio a caiano.
in the meantime charles defeated francis and imprisoned him for a year. when he released him he asked for his two sons, henry and francis as hostages as a condition for the release. the two bys spent 4 years in prison because of that and were released as a result of the ladies treaty, called like that because it was done at the initiative of francis' new wife, leonora (sister of the emperror) and the emperror's wife, isabel.
catherine was moved back to florence in a monastery of benedictines, who were offering education for the young daughters of the high society of italy. the nuns are recorded to have loved little catherine a lot. but the medicis were suffering a crisis of popularity and lots of people tried to get catherine out and kill her or send her to a brothel (!). the florentine government decided to transfer to santa lucia, a safer convent.
in 1530, her uncle, clement 7th arranged for catherine to be taken to rome. at that time the rumour was still going around about her marrying ippolito. but at that time he was a cardinal and his uncle had better ideas so he sent him as a papal legate to hungary. a number of suitors were considered: ercole d'este (son of the duke of ferrara - also son of lucrezia borgia

, james 5th of scotland (catherine's mother's sister had married a duke of albany from scotland), henry fitzroy, the bastard son of henry 8th. at some point the pope wanted to marry her to philibert de chalon, prince of orange who had helped him with a few battles, but the prince died soon after that. other possible husbands were federico gonzaga (duke of mantua), guidobaldo delle rovere (prince of urbino). the most serious was, apparently, francesco sforza but the pope had some reservations.
it was at this point that francis 1st suggested his second son, henry (duke of orleans at the time). he offered to take catherine until she was fit to marry and wanted as dowry pisa, leghorn, reggio and modena along with parma and piacenza... clement accepted the contract but refused to hand over catherine until the actual marriage took place. the king then changed the ambassador to francois de tournon who was a cousin of catherine's who got ill on the road and reached rome very late. by the time he got there, francis had signed an alliance with henry 8th meant to pressure the pope into granting henry his divorce. so the ambassador also had to handle that because the two kings agreed on approaching the pope together about the matter. the pope agreed to talk to them as long as the emperror charles didn't find out about it. on the 21st of january 1533, the pope announced officially the marriage between catherine and henry.
catherine returned to the medici palace in florence which was administred by a guy called ottaviano de medici. she started participating to social events such as welcoming the new duchess of medici, margaret of austria (illegitimate daughter of the emperror). it was around that time that giorgio vasari, sebastiano del piombo and bronzino all painted her portrait. she was described as small and thin, with huge eyes and not very nice facial features. she seemed to have a little bit of malice. when vasari was painting her portrait for the french king and left it unsupervised she added some colours of her own, practically destroying it. he didn't seem to mind, though, he wrote he was 'very devoted to her'.
the wedding preparations began. on the 28th of august she got lots of jewels, present from francis. her dowry was estimated at 100000 gold scuds (? how are they called in english) plus 30000 more in exchange for her rights as a medici, an anual rent of 10000 scuds and jewels estimated at 27900 scuds. she left florence at the 1st of september after a farewell banquet. she was taken to villefranche where she waited for the pope. on the 11th of october catherine reached marseille where she was welcomed officially by the french. francis arrived on the 13th of october. he had a long meeting with the pope but no-one knows exactly what they talked about, except one project of some sort of offensive alliance. on the 27th of october the marriage contract was signed and the next day the actual marriage took place. the two newlyweds (14 both) were led by king eleanor to the nuptials and it is said that francis witnessed the consumation of the marriage declaring that they 'both showed value at the comfrontation' ( :-/). the next day clement is supposed to have found them still in bed and said they looked satisfied...
most of this is courtesy of rj knecht, with some added comments by yours truly

as you can see not the happiest of childhoods and most definitely not the safest...