If you are looking to use the Helios 44 as your "50", actually it is 58mm then you can make up a set of 37mm Mir 1b, 58mm Helios 44, 58mm Jupiter 9, 135mm Jupiter 11A or 37 and 200mm Jupiter 21m. As these are all CZJ based you can usually swap in CZJ Flektogon, Biotar and Sonnar.
You need the powerhouse computer to work with 4K+ video in Resolve 14. If you aren't upgrading the camera then the computer seems irrelevant. It isn't that it is impossible to shoot good video with a Rebel, people can and do. Lens upgrade? Maybe. One or two Yongnou, perhaps vintage glass, Helios, OM, CZJ, FD etc. You would still have a lot of change left. Certainly make sure that you have decent sound kit, perhaps lighting too.
The most important part of the entire system is you. Even for the guys here with the most expensive kit, they are still what makes their stuff so good.
Had a think about this. CR files are proprietary Canon aren't they? If your Mac isn't set to handle them then they won't show up. The Mac hasn't a clue what they are. I think that you have to use the Canon software or at least install what you need to for the Mac to know what they are.
You ought to be getting both even with Magic Lantern. I have ML on my EOS-Ms so I'm in similar territory. Will you actually be post processing photos? If you are not then don't worry about RAW. If you might be, then shoot in RAW perhaps don't bother with jpeg. You will get jpegs out when you batch process at the end anyhow (assuming you use Canon's software). If you are storing on Google Photos, then store them up there in RAW, Google handles them just fine.
RAW is great because you can adjust white balance, change contrast and lots of other functions that i haven't found yet.
ML is great because it gives you focus peaking and all sorts of aids that your camera doesn't have (and my hint to Canon is, should have). Not got into RAW video but I have used the anamorphic tools.
Look at getting picture profiles onto your camera. I have one that is optimised for getting it right first time without post but I also have Cinestyle and Marvel which are both flat profiles for video. Cinestyle is great as there are LUTs to convert to film looks and other things.
Filmic pro is available for Android too but not my phone. (Vernee Thor). Access to flat colour profiles via Filmic sounds impressive. There are Android phones coming through now that use more than one lens to create a shallow depth of field. The next few years will see great changes (as they always do, I suppose)
One thing to be aware of. Many of the Takumars and Super Takumars around that focal length (50, 55 etc) are radioactive due to the thorium put in the glass nearest to the camera. It's not really a problem. Just don't eat it or store it down your boxers.
Excellent lenses. I have 3. They don't get the use they ought as my preference in my own collection are the Helios, the Contax Yashica and CZJ. On bang for buck, the Olympus is still the star, available at pocket money prices.