Hope this is the right section for this

I've been thinking of buying the Family Tree Maker software package but wondered if anyone here had used it as I have a question about it. Obviously individual bits of information like census scans, photos, documents ect have to be backed up elsewhere eg on disc, but once you've started making your family tree, if anything happened to your PC, would the tree still be available on the Ancestry website so you could sync it and get it back on your PC after fixing it and installing the tree software again? Or would you have to start building it all over again? Also if I install and make the tree on my PC's internal hardrive, how easy is it to transfer it to an external HD? As I may want to do this in the future.
Thanks.