Glad to hear you are feeling better, and out of hospital.

A blood clot will not form in a healthy artery. Although blood vessels lose elasticity with age, and become more prone to this problems, you are still too young for this.

Most likely what happened (and its the most often case in coronary heart attack) you had plaque build up on the artery (atherosclerosis), this plaque can become brittle and when breaks damages the arterial wall making a blood clot. So, while you didn't have this directly due to cholesterol, indirectly it was what created the plaque as most of the content of the plaques is cholesterol.

I would suggest a leg doppler ultrasound to assess the plaque build up on the leg artery, this will give an idea of the level of atherosclerosis you may be suffering.

Morning erections are not a indicator of anything. With the stress you had last week it is only normal. If you start TRT I would suggest nebido as it may have better results in the problems related to polycythemia and e2 conversion.