Yes, you can. Taking paracetamol improves the effect of paracetamol, which is why they give you both in hospital. However, I wouldn't take tramadol at all, without checking with a doctor first.
No, it's always good to buy only one type of analgesics that is not prescribed by your doctor
Yes it is fine to take paracetamol and ibuprofen together as long as you remember that ibuprofen should...