The pattern of these exams are very different from that of the UPSC CSE. Hence, if you dedicate too much time preparing for them, you might end up shooting too many birds with one bullet. If you are confident that you can manage all of them together, then I would say go for it. My friend Razim, who is in IRTS had been selected for SSC CGL the same year he got selected by the UPSC. Thus it is not without precedent.
Depends completely on your skill and aptitude. Nothing wrong in it. I did not do it.