Included board darts can range widely between 17-22 grams, if they are brass and stubby they are probably close to 18 grams. Everyone will have a sweet spot for weight, length, material, etc its best to find a shop that will let you try them out before you buy, they can also make recommendations. The most important thing to remember though is more expensive darts do not make better darts, I thoroughly enjoy playing at the local bar with crappy house darts and trouncing people with their slick high priced darts.
A few recommendations though are
-avoid plastic in all parts except flights
-get a "dart tool"
-avoid brass if possible as they are annoyingly heavy in a decent length
-get spare parts, flights, barrels, shafts, etc you will break alot when first starting out
-start cheap and get a variety of weights, lengths, flights to find out what your preferred configuration is then fine tune it from there
-go to the bars and find good players to play with, best classroom there is
-aspirin for the next day as you will work odd muscles in your arm that will hurt like hell if you play for long hours