Can ECG result alone can assure you that you don't have any heart disease?

Absolutely NOT!! You can have plaque (fat) building up in your coronary arteries (arteries on your heart) which can block blood flow to your heart and can cause an MI (myocardial infarction or heart attack). Blockage of the coronary arteries is not read on an ECG it can be read through an angiogram. ECG just reads the rhythm of the heart and determines if your heart is beating normally or if you have some sort of arrythmia or abnormal beating heart.

No a resting ECG doesn't exclude heart disease

no

you need to look at the arteries if blocked and that the specialist performing the heart test by putting dye into your main arteries to check if any blockage.

The ECG only tells you the beats and if any heart skips are done.

NO