Thanks Haasman for your reply !
Anyway as I'm consider a dumb to this engine part, appreciate if you could provide more detail or image if available for the items below :-
(1) Sounds like you should check your throttle linkage for smooth movement AND lubricate it. It is recommended to use ATF fluid for the pivots and ball joints
Answer - Where is the throttle ?
Is the ATF fluid same as the power-steering fluid ?
DO I need to spray them or how ?

(3) Often starting problems are related to cap and rotors. Is yours a fuel injected model or carb? If carb, after checking the rotor/cap and plugs, I would make sure the auto choke is working properly. Best done absolutely cold (first thing in morning) with the air cleaner off so you can see the choke flap postion inside the carb throat.
Answer - Mine one is injection, can I use the same method as above ?

You do not have to change the relay when you change the fuel filter. Often a "crush" washer is used to attach the lines. Be sure to install a new one if so used.
Answer-What is the best timing to change the fuel-filter ?
is it same as the fuel-pump relay ?

Sorry for the siily question but I'll try to learn quickly.
Thanks a lot for your kindest help.

Kareem.