You should be fine to feed syrup. I would feed 1:1 so they can consume it and not have to dilute it first.
Packages should be the last choice if one can help it. I am a strong believer in local acclimated stock. With packages, the first month they are in decline while brood is reared, then it takes awhile for them to build back up to what they where when you got them before you will see them grow. Not to mention the chances of getting SHBs in your apiary.