@Davide654
I host long stays and, like @Helen3 , I would not consider taking the proposal to split an eight month stay into 2x four month stays. Four months is far too long to have dates blocked with no guarantee that the guest will end up using them. Although in general, it's obviously better for a host that you cancel with as much notice as possible, in that particular scenario, it actually makes it worse because, if you ended up not using the second four months, who knows how many other bookings the host could have lost in the meantime?
Also, @Helen3 is correct that long term stays are charged monthly. I don't see how splitting the stay makes a difference to your wallet, so if a guest asked for this, I would take it as they are not sure they are going to stay the whole eight months are are trying to avoid paying penalties under the long term cancellation policy.
Also, as utilities are included (as opposed to with regular rentals, as you mentioned), it doesn't make sense that you would ask about these to "understand costs". I would find it strange if a guest wrote this to me. Of course, it is not strange to ask if there is sufficient WiFi, heating and hot water, but these things are normally listed already under the amenities of the listing. If there are any real issues with these, guests would normally mention it in the reviews.
To me, the most important things when a guest approaches me, especially for a very long stay, is that A.) they tell me something about themselves so I can get a sense of their personality and also what their schedule would be like, but I host in a shared home, so that's probably more important to me than a host renting out an entire unit, and B.) that they have read the full listing and house rules. I don't accept any bookings until I feel pretty certain of this.
It also doesn't hurt to say something nice and particular about the listing and why you want to stay there and make sure to address the host by name. This helps the host to know if you'll be a good fit and also that yours is not just a message you are mass mailing to loads of hosts. Unfortunately, there are a lot of guests out there that are time wasters, i.e. can't be bothered to read anything and take up time asking hosts questions that were already answered on the listing.