Beginner questions 

Is gene therapy supposed to affect the whole body, or is it supposed to only affect those cells where it is neccessary (e.g. some gene defect causing gastrointestinal problems only requires gene therapy in the gastrointestinal tract)?
Do cells treated with gene therapy participate in mitosis? Will copies of treated cells have the same treated DNA?
Is it required to constantly get gene therapy to keep the desired result, or is the purpose that once cells are treated the therapy is self-sustaining?
Is there a "combat"/"balance" between non-treated cells and treated cells? Are genetically-treated bodies technically Chimera (genetics)?
Does gene therapy have the target to completely transform the DNA of the patient?