Templatestudio isn't vs.net, and it will never be vs.net, because building intellisense for C# etc. is very hard.
Writing templates should be done this way:
- write the code you want to generate for one entity by hand. This can be done in vs.net
- pick that code and covert it into a template by 'templating' the parts which are specific for that entity and which are repetitive, i.e. should be generated with a loop, like all relations
- run the template to see if it works out well
You'll see that step 2 is actually pretty small. The problem with writing template code inside the template editor is that if you don't know what the output should be, writing the template is actually pretty hard, and time consuming: you have to regenerate the code a lot of times which is not that productive.