Greetings, and thank you for your question! I see you are offline right now but will try to provide you with some information from which to start. First off, for most people Ativan does not alter blood pressure directly. It works on the GABA system in the brain, and the blood pressure systems are different (NE and EP, to be specific). Now, Ativan can relieve anxiety, as you have found out, and that lowered anxiety can translate to lowered blood pressure, but it ought not mean blood pressure that is too low. Typically, Ativan slows breathing rate and effort rather than blood pressure.
You can certainly wean off the Ativan, but given the length of time you have been off it, I'd do this under guidance of a physician. However, cutting out 0.25 - 0.5 mg at a time, or just spacing out the time between doses (which is effectively the same as not taking as much) is a very safe plan to avoid rebound anxiety and withdrawal symptoms.
For question 3, exercise in the long run usually lowers blood pressure (or keeps it close to normal), but during the actual exercise itself and for a short recovery period after the blood pressure and heart rate will be elevated - this is normal and desired.
Hope this gets you started! Please let m know if you have further questions or if I may be of further service!