Homemade marcipan is easily better (but unfortunately not cheaper) than store bought, the reason is that store bought marcipan in general skimps on the almond content (because it is expensive), but then making it yourself, you can experiment with the right content and also you can experiment with taste additives you like.
Yes, this particular marzipan is made with rose water.
Almond extract is a must to enhance the almond taste in marzipan, however my favourite optional taste additives are rose water and vanilla.
Marzipan can easily be eaten raw as is, however in general it is used as the base for an endless variety of interesting candies and especially baked marzipan is absolutely delicious.
Notice that there is another product nearly the same as marzipan called almond paste. The difference is that almond paste is more soft.
To make almond paste (that is : soften up the marzipan), you can use several different techniques :
Marzipan should be wrapped airtight in film and then preferably put in an airtight container. If kept airtight, marzipan can be stored up to 2-3 weeks in a dark cold room, up to a month in the refrigerator and up to 6 month in the freezer (then keept in the freezer marzipan tends to dry crack, which can be mitigated using wet wrap or one of the above soften techniques).