Basic rules for EU membership?

Question

What are the basic rules the countries need to abide by and

what do they get out of being a member?

Why does the EU not allow certain countries in?

Answer 1

follow abide the principles of collective leadership, political control, centralized  economic policies and programs, agricultural quotas / restrictions eg bananas must be of certain length, color etc.  this is to ensure equal competition for all growers.   one single currency, various other cultural and demographic issues that will make EU a big country.  u get loans, get special research grants, help, citizens can work anywhere in EU, and many other perks.

some countries are still not in 'cos of their communist legacy and slow in democratic / economic reforms.  turkey is not in 'cos its muslim and the largest population.  hence it will become suddenly very islamic --- so it has to be delayed...