1)It sounds like you've had many of the right tests for a stroke workup including blood work for a clotting disorder. Other tests to consider include homocysteine level and autoimmune panel to look for diseases such as lupus which can cause stroke. An angiogram to look for vasculitis may also be a consideration depending on your doc's suspicions for this disorder. Another possiblity (though less likely perhaps given your multiple stroke risk factors) is could this be MS rather than stroke? Visual loss could have been optic neuritis and the "stroke" in cerebellum could be a plaque. Certainly don't mean to alarm you, just let you know that there may be other possibolities. There are special types of MRI that can easily distinguish between a stroke an dMS. Consider a second opinion by a stroke neurologist at a major academicor clinical center nearby.
2.Absolutely start cholesterol lowering medication such as lipitor especially because the protective effects of estrogen on your cholesterol level will soon be lost after menopause. This of course does NOT mean that estrogen replacement will lower your stroke risk. But it means you have to be extra careful with the cholesterol. Eat healthy and get exercise. Stop smoking if you do. And continue the baby aspirin daily/ Good luck