Instead of flooding the discussion I will ask you here instead. Is it possible to download IR, SR and SCS using BWS? Or do I need to separately manually download them in the order you mentioned in the familiar link you sent me?
Personal messages work better for these questions, but the answer is yes. BWS can install SR, IR, and SCS in the correct order and make them work together.
Manually downloading them also works, and the SCS and SR readmes will both explain what order to install them in.
If you want lots of mods, go for BWS. The whole installation process could take 2 days (see the BWS thread in the General Modding section) but BWS has lots of great content. If you just want those three mods, install them manually; the process will take maybe an hour or two.