even working within them is possible with certain sectors and specialities. Sure an expat can't get a paid job planting rice etc but his skillset is more specialised
I haven't done anything on that yet but have been told already I won't need to pay any taxes here on money I bring in as already taxed in the UK but I may still need to file a return
The type of business is mostly irrelevant as the right type of person can make a business work as they plan carefully, research markets and competitors, do trials perhaps, and they certainly don't jump into something with only hope and blind faith. It's no different to any other country really. In any country if 10 people start the exact same business with the same start up capital there will always be a few that fail miserably within a few months, some who may last a year or so and maybe one or two that really make a success of it and build a profitable business
no age restriction. I got one as moved here in my 40's and wasn't married so it was the best practical option. The price has more than doubled though now for them compared to what I paid 4.5 years ago