Yes, Science Vessels have the most Science BOffs and have the most ability to heal.
I'm not sure what Science Officers get as far as abilities in space but I do know ships. I would assume that it works the same as Engineers and Tactical Officers (Defensive and Offensive respectively).
Whats the best way to go about been a healer in STO ?
I know that science is probably the best for healer on the ground, but is that the same for healing or fixing ships whilst in combat to ?
You might want to do a forum title search on the word "Leeching". There was a rant about people soaking up the sector victories and not helping, and a few dedicated healers in science vessals chimed in about the behavior of healing speced Science vessels. I have seen science vessels behaving that way a 'few' times myself: not doing a lot of firing, casting some HOT when lead ships agro a pack. They reported problems that auto heals sometimes targeted mines in error of teamamtes.