I have fastai v1 installed on my machine. Can I use the ML course notebook with fastai V1? Or do I need to create an environment with fastai v0.7 for the ML notebooks?
You will have to create a different environment for ML course. But with some effort you can also work with fastai v1. I personally preferred fastai v1 even if it meant more work, as there are a lot of bug fixes and you have to get used to v1 as well.
SO I should do ML course by Fast.ai v1 and seeing errors from forum if some feature is not available?
fastaiv2 is also mostly completed. It will be released in July I think, so may as well try that. fastai version should not matter much. If you did into the source code of v0.7 (which I think was used in that course) and see the source code of v1.x (if it mostly the same for tabular).