Hi there, my name is Matt Sergei (do call me Matt) and can create your R markdown reports (26 years a webmaster and IT developer, scripting R for 5+ years).
Now I understand you want PDF outputs with nice tables. I would like to see a sample report - if it can be scripted using knitr::kable package (and kableExtra) then this should be an enjoyable task. Of course I'll use RStudio for all the work.
I use Git occasionaly and it will not be an issue to push the updates.
Regarding hourly rate - I always rather work for a fixed rate, with tracking only output hours to adjust if needed. Output hours are hours with focused output work, not any bug fixing, potential additional learning etc. So 250 USD/week would be fine for 10 hours and so on - Freelancer tracking software really influences clear and smart thinking and in my case prolongs the necessary time to complete.
So I believe fixed rate is more fair to you (and it was for my clients here in past 16 years).
I have to add I'm in CET time zone (ET+6) and currently am limiting daily work to 7-8 hours for my family and health. We should cooperate fine with that, I finish at around 7-8 ET daily.
Looking forward to your reply,
Matt