Hello
I think that at one point or another it will be unavoidable to tell your physician that you are trans. Questions about your last period, their regularity, inter-period bleeding, your last papsmear and colposcopy eventually will pretty much always come up in a general checkup. As others have said, it's important to be honest with your doctor to avoid misdiagnosis and unnecessary tests. If you tell them for example that your mother and sister had breast cancer at 45 years old, they might ask you for a yearly mammography from the age of 35, exposing you to radiation for no reason. Last, as it has been mentioned, it is important that your physician knows the medication you are taking, to evaluate possible interactions, as well as past surgeries.
As for blood pressure values, I don't think there's significant differences between the sexes. I reckon the red blood cell count should be modified after HRT, since Testosterone induces erythropoietin, which in turn increases red blood cells levels. If we administer then testosterone blockers and estrogens, erythropoiesis should decrease. However, I couldn't find scientific papers to back this up.