Some complex encounters do not necessarily says a monster ambushing you but is a strength test to a monster attack. Do you get to use bonuses related to combat encounters ie a weapon?

An investigator can only perform one component action per round, does that mean one of the same card or out of all component cards only one can be used? Ie investigator card limited action is used they can not then perform feed the minds. Or if they plumb the void then cannot feed the minds either.

Does Charlie ability allows an investigator perform an action more then once as in one Charlie ability the investigator travels one space, then on that investigator turn he can still travel once more? same for various component actions, same spell twice, or two different spells? Yes everyone wants to find a way to get in another feed the minds

In card encounters where it says something like "A Star Spawn attacks you, [Roll Strength]", this is merely flavour, no combat encounter is taking place, only one success is required, you do not refer to the Star Spawn monster token in any way, and do not use any components which interact only with combat encounters. You can still use bonuses like the +1 Strength from the Hired Muscle, which is all the time.

I am not 100% sure what you mean in your second question, however I believe that you are asking whether you may use two different actions from two different component cards in a turn. Yes, as long as you do not perform the same action twice you are OK.

Charlie's action is fully explained in the rear section of the rulebook, it gives the targeted investigator an extra action immediately in Charlie's turn, this can be any action, but the investigator cannot use the same action twice in the round, so he must perform three different actions (Move, Shop, Rest for instance). In your examples you can not travel twice, you may cast two (or even three) different spells.

Hope this helps.

If the encounter calls for a Strength test flat out, and doesn't mention a Combat encounter, then no, you can't use Combat encounter bonuses. Personally I think it's a mistake to have monster attacks not resolved as Combat encounters, but that's just my opinion.

You can't perform the same component action, but you can perform different ones. So you could both cast Feed the Mind and Plumb the Void, or negotiate a fellow investigator out of Debt and another out of prison. You just couldn't do the same twice.

Charlie doesn't give doubles, sorry.