The general rule AFAIK is 1 cabin baggage + ( 1 small handbag or 1 small backpack or a briefcase or a laptop bag). src: CX Cabin Baggage
So if the camera bagpack looks like a standard school back pack should be ok.


I always bring some asam, helps with traveling sickness.

I'm not sure.
I did travel Penang --> KLIA using MAS and then KLIA --> HKG --> LAX using CX previously, and could checked in my bags at Penang that goes all the way to LAX, but this was a ticket arranged from an agent who knew my final destination is LAX.

I think roaming is not needed unless you're expecting someone important to call you on your Malaysian number.
For local calls on foreign soils, a prepaid local sim card is usually cheaper, and definitely much more convenient. Plus if you have local friends/colleagues, can give them the number and they can easily call you too. Some situations, e.g. calling cabs, reserving tables in restaurants, is much easier when you have a local number.
For long distance calls e.g. back to Malaysia, generally those long distance prepaid cards are more worth it unless it's a country your telco has special arrangement with.

Legally, you're not allowed to bring any meat product, processed or otherwise, to EU from outside of EU countries.