Welcome and I am sorry about your daughter. I take it you mean Parry-Romberg's rather than Raynaud's in the last question?
Here's the problem, there is no clear answer to many of your questions, in particular the efficacy of methotrexate. The only way to decide whether a treatment works is to try it, the only way to decide which is worse, the symptom or the side effect, is to try it. Bearing in mind en coupe de sabre can disfigure I would have thought some serious side effects would have to beat this.
A lot of scleroderma is a gray area, what works for one doesn't for another, what happens to one doesn't happen to another and perhaps most frustrating of all is that what one doctor thinks another most certainly does not. We call the systemic form a tailor made disease, those with it snowflakes as everyone is so very different.
I appreciate you are looking for something concrete to go on but there's precious little of it when it comes to scleroderma. At some point you have to make a decision based on the information you have rather than searching for more of it. If the doctor is a good one then they will be able to help guide you and advise you.
I have had diffuse systemic scleroderma for 7 years now and I understand wanting things cut and dried. Taking things one day at a time is a very good idea, scleroderma will make sure it gives each day plenty worry of its own for sure! We don't need to borrow any from tomorrow!