第一个问题

First problem

string path = Path.Combine(textBoxFolderToWatch.Text, FileName);
string path2 = Path.Combine(textBoxtogo.Text, FileName);

非常简单，即使您不阅读文档

第二个问题

Very simple, even if you don''t read the documentation

Second problem

private string GetPath(string path)
{
  int version = 1;
  string fileName = Path.GetFileNameWithoutExtension(path);
  string folder = Path.GetDirectoryName(path);
  string extentions = Path.GetExtention(path);2
  while( File.Exists(path) )
  {
     path = Path.Combine(folder, fileName + version++);
     path = Path.Combine(path, extention);
  }

  return path;
}