Congratulations on your new Syrian hamster, good choice and I'm sure will bring you heaps of enjoyment.
Can you get 'Harry Hamsters' dry mix? It is a vailable in the US and I'm sure online too (Petsmart), this isn't a bad mix, it does have sunflower seeds in it but that's ok, it's a complete balanced food mix for hamsters. Lab blocks are boring in my opinion.
Stay away from feeding crappy treats that you can buy in pet stores, too sweet, too sticky, to fattening..unhealthy. Feed small amount of fresh raw veggies..start slowly as not to give hamster tummy upset. Carrot, peas, green beans, broccoli, cabbage etc. Fruit can be given but feed few and far between..teeny amounts as an occasional treat: apple, pear, melon, peach..making sure you discard stones and pips etc. Offer nice hard healthy dog biscuit every so often, great for teeth and provides activity in your hamsters routine.
Take your time with your new Syrian, be patient and you will be well rewarded..there is no such thing as a vicious hamster, just a bad human who either created a bad tempered and frightened hamster or a human has an ill hamster.