I'm not sure if development questions are not welcome on Drupal Answers.
I cannot find any suitable tags related to development. The best matching tag is developing, but that one will be removed. So which tags should I use?
Drupal Answers isn't an appropriate place to ask about general software development, but it is definitely the place to ask about Drupal development.
I imagine that the developing tag is to be removed because it's too generalised; no-one could reasonably ascertain the category of a question given just that tag name.
Most importantly, the tags you use should be relevant to the question you're asking.
For example, if you are experiencing problems while developing a custom form, an appropriate tag would be form-api. If you're trying to install a custom field through code, and it's not working, field-api would be appropriate. And so on.
If you're still unsure, have a look through the questions currently on the front page of the main site. A lot of them are questions about development, and by looking at what they have been tagged with, you should be able to get a good feel for your own questions.
As per the FAQ, the following questions are on-topic, on Drupal Answers:
The question needs to be about Drupal; any other question is off-topic.
developing is a tag that is too generic, and it doesn't communicate anything to who answers the question. The fact you are developing a module, or you are asking the code you should write in a text area that asks you to enter PHP code, influences minimally the answers, and it doesn't deserve a tag.