There are lots of other people who I am sure will jump in with advice for you.
However, one thing you didn’t mention was the tax situation. If you are a non resident you pay tax on the rental income at, I think, 35%. Also you cannot, as a non resident, claim any expenses back.
I would not recommend anyone to invest at the moment in an off plan purchase, and would not believe anything an agent/promotor told me about potential rental income. You only have to look at all the empty houses and apartments along the coast. If you are buying it with a view to living in it, or using it for holidays yourself, and are not having to pay for most of it with a mortgage, then it may be an opportunity for you. Don’t rely on rental income to cover your mortgage, you could catch cold.
If you succumb to an inspection trip, please bear in mind that the people taking you around the developments are working purely for commission. They pay all their petrol expenses themselves, have the job of picking you up from the airport and taking you back again, and only get paid if they make a sale. So there is always a hard sell situation.
I have some German neighbours who rent their small villa out themselves, but only for about 12 weeks of the year, not necessarily in the high season. The villa is inland and has no pool, and prices vary from 280 to 400 euros a week, depending on time of year. They also have to pay someone to clean the villa when the visitors leave and to do the laundry.
Good luck with your venture.