No, there is no extension included in the delivery.

There are various smartphone holders on the market but these have nothing to do with this tripod and must be purchased separately.

According to the product description in German it does come with the extension arm :) "Das Set besteht aus dem Scout MAX Stativ mit einer maximalen Höhe von 157cm sowie dem 31cm langen Stativauslegearm von mantona."

Should be there.

Yes, it is compatible. A great tripod, I can recommend it. Rotates in all directions.