I have heart disease. will strength training help?

Very likely yes: In many cases, after having a heart attack, etc, strength training can improve your exercise tolerance and circulation, decrease edema (swelling of your legs), and help you maintain a normal blood sugar and weight. However, it is important to make sure your your blood pressure is well controlled first and that your cardiologist approves (depending on the type of heart disease that you have).

Yes but take it easy: Weight training and cardiovascular work will be healthy for the heart, but the latter should be monitored in a cardiac rehabilitation program and the former should be enacted with light weights to work the muscles but not tax the heart too much.