In the four part of your questions the word “to promote” is used. It is ambiguous word. You need to explain it that what do you mean by it, how you would promote and then for whom you would promote it. How do you do your dealing with them? After writing the complete details, you may be answered. However (1) if you adopt lawful method to promote as well as if your dealing is lawful with real company then the income earned by it will be halal for you.
(2) The income earned on halal pattern by promoting sun glasses, shirt, frame etc containing no picture of living beings is halal but since it involves propagating film and songs hence it is not better to adopt such types of profession. It is mentioned in the holy Quran:
وَلاَ تَعَاوَنُواْ عَلَى الإِثْمِ وَالْعُدْوَانِ [المائدة : 2]
And do not help each other in sin and aggression.
(3) You can promote those non-Islamic educational courses mentioned in the question as well as its income shall be halal for you provided the method of promoting is as per the Sunnah, but since the education system of these courses contain unlawful elements such as music etc hence they should also be avoided.
(4) Basically there are some conditions for the dealing to be lawful which are as follows: (a) product and price both are halal. (b) Product is in existence which can be handed over. (c) The dealing should have no condition that is unlawful and that annuls the contract. (d) No wrong thing is advertised by the product etc. But presently there are too many ways of business and everyone is not able to differentiate lawful from unlawful; hence you should consult the Ulama about the products that you want to promote by telling them complete details.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband