Hello, welcome to Condado - I am sure you will enjoy owning a place on the resort.
We bought last year and the services were organised by the lawyer dealing with the sale, we used PALS in Mazarron port and they were recommended by Andy at Condado Invest. If you are using either of these they can help. Water will be with Socamex and electric will be with Iberdrola. A company called A2Z can provide internet to your apartment for free http://www.a2ztelecomunicaciones.es/
We bought our air con through Euronics at Camposol. Everything is fine but we have had to call them out a couple of times for small issues which they have resolved promptly as part of the service. Check for offers when you buy, we ended up buying 3 x 12000 btu units as it worked out cheaper than the 1 x 12000 btu and 2 x 7000 btu that is usually offered as a pack in the 2 bedroom apartments.
We did not buy a furniture pack and we are happy that we did not. We bought our white goods from Paco Molina who are at Al Kasar, fridge freezer, washing machine, dishwasher and microwave was 999euro I think. Otherwise Euronics in Camposol can help with all your white goods.
We bought all our kitchenware from Ikea at Murcia, its worth a day out there to get it all. You can buy the Malm drawers for inside your fitted wardrobes which is a really cheap way of gaining drawer space. We bought our beds and other bits from Furniture Plus up by the port, opposite Lidl and if you are there you can get bedding, curtains, etc, from Yorkshire Linen which is next door. Having at least one storage bed might be worth considering, its really handy to keep stuff hidden away when it is not used much.
We didnt use a mortgage and our buildings insurance is included in the community fees, i.e. we dont pay extra for it, but I believe if a mortgage is involved you may need your own. Mileniun can provide insurance I think, under 70euros per year for contents I think it was.
No hidden expenses that I recall although do make sure you have more than enough money in your bank account to pay for all the setup costs and community fee's. We were a little short and had the water cut off without notice and had to pay an extra reconnection fee of 50 euros. Not a lot but annoying nonetheless.
Im sure other people can offer more advice. Good luck with your purchase!