I use only wacom and dont touch a mouse for anything at all. Mind you, I only do 2d. I cant see any reason why a wacom would not be just as suitable as a mouse for 3d though.
Here are my tips.
1) Dont use mouse mode at all. Once you get used to tablet mode (or whatever it is called) you will never need to use mouse mode again. I do not agree that mouse mode is more suitable for general computer use. It is increasing the repetative movements which are causing you to get tendonitis.
2) Only use an A4 or A3 size wacom. not smaller. The larger movemements you make, the less damage you are doing to yourself. I consider A4 to be a good comprimise because an A3 is so big that you will probably have to buy a bigger desk.
3) Buy a wrist splint and get used to wearing it while you work. It feels a bit funny at first but it stops you using your wrist and transfers the movement to your elbow.
4) I went to a chinese medicine shop and got this very smelly liquid made by kung fu fighting monks or something. Every hour or so, I stopped working and massaged it into my hand and wrist. I dont know if it was the breaks, the massage or the smelly monk stuff but my wrist got better very quickly.