I will try to help by describing a typical F1 team’s structure. Typically the Technical director will have the Design Office, Aerodynamics, Vehicle Dynamics and Race engineering reporting to them. There will be a production director (amount of internal vs external production needs to be carefully managed) who will have composite, metallic components, inspection, sub assembly and car build reporting to them. The race team manager will have the race mechanics reporting to them, possibly along with logistics. HR, finance and marketing will be separate departments reporting to the CEO.
R&D doesn’t really exist as a department (the name does but it is not correct to call it that) as R&D is done by all departments in the areas that they need to develop new ideas in. When a team calls a department R&D they typically mean the Test department as that is where the 7 post rig, mutil axis corner rigs, damper test rigs, materials test rigs etc are held and used. Mercedes tried to create a real R&D department to do research and development around 6 years ago, but it was a waste of time as they just did bits of what other departments did and delivered little.
I don’t know what the relative spend is across the departments of a typical team. As a rough idea, a team like Mercedes will have around 150 people in Design, 200 people in Aero, 40 people in Vehicle Dynamics, 5 people in HR