not sure if you have left for your holiday but remember holiday is to have a good time and not be stressed over the use of your new camera
when all fails, use the green square - auto mode
have a good trip
most of the newbies tends to be excited to buy things. which only rare you'll get satisfied in the end. unless you get lucky to buy the ones you will really need.
my opinion, use the kit lens. if you get to be confident on how you use aperture, shutter speed, iso and stuffs, that is where you start looking for reviews on which lens is good for your portraits and landscapes.
But still, 50mm f/1.8, i doubt everyone loves it. aside from the quality photos it produces, its very affordable.
does the sigma 70-300 comes with IS? sheesh i was aiming for it until i saw this.