My aunt used a surrogate for her son (now 18). By my observation, she felt just as attached as any other mother I've known or talked to. For instance, her son was diagnosed as learning disabled and she went to extraordinary lengths to get him the care he needed.
As for the immediate post-birth mother/child bond, if a woman wanted to experience it without pregnancy, she probably could. She could definitely experience breastfeeding .. and postpartum depression too. These are all responses to hormone levels -- progesterone, estrogen, prolactin, oxytocin, etc.. -- which could be mimicked via oral supplements or injections.
Another consideration is that fathers do not experience pregnancy (directly) but bond with their children. Sometimes they feel that bond immediately, sometimes it takes a little longer, but I don't think that the time it takes to develop a bond is a good indicator of its strength.
As for the children, their attachment to a caregiver is constrained by their brain development. They usually don't (or can't) show their preference for one caregiver over another until about 6 months of age. Attachment development varies from child to child but seems most intense between 1.5 to 2 yrs of age. (for more info look up John Bowlby or Mary Ainsworth)