There are plenty of players in Phuket and Samui. I also heard good things about Ko Chang-am sure not many poker players are there is any, but never was there. 4g network like Varune said is awesome, but you can also get good and fast internet going. I had 30/30 or 50/50 broadband in some places and I think they have fiber optics even on some islands, so just get that if you stay longer.
For shops it is easy to get whatever you want. You have huge shopping malls like Central festival and chains like Tesco, so that will not be a problem. As far as I heard you also have quite high quality private hospitals, as there is a lot of medical tourism, so you can apply maybe haha.
For renting out a place I mostly used an Agent in Thailand, but also AirBnB and if you search for FB apartment or villa renting you will find some good things as well. You can PM me and I can send you some numbers of agents in Phuket and maybe I still have for Samui as well, but otherwise you will find good contacts online.
