why present is used here? Both are future events is it because it is an habit to play both festivals and to tour USA and Canada for the band or is it because are leaving indicates that these events take place in the future?
So lets take a look at the statement and sort it out
*are* (will be) leaving on a tour of Italy tomorrow, for 10 days, after that we (will) tour The USA and Canada for two weeks.
When we come back we (will) play Fuzzville in Benidorm. Then (we will play) some gigs in England, Holland, France, Scotland.
Our album will be out on Slovenly next fall.
Here we can see more clearly what is happening The word will has been use in some places but only assumed in others. However the inclusion (assumed or actual) alters how we write the rest of the text. Once we include will then we can use the base form of the main verb.
Note The assumed use of words often happens in spoken English, and whilst there are rules for some occasions, it is more often the speaker/author's assumed familiarity with the subject, by the recipient/reader, which defines the amount of descriptive text. This use of assumed words/phrases make comprehension particularly difficult for Non Native speakers.
Will and shall: form Cambridge English Dictionary
Will and shall are modal verbs. They are used with the base form of the main verb (They will go; I shall ask her). Shall is only used for future time reference with I and we, and is more formal than will. …