The joystick is a standard one and not the one from the 1DXIII (as much as it would have been great). Blue circle is depth of view preview button but it will probably be assignable. The yellow port is for the remote cable release, Both similar to the 5Div layout.
8K30 needs ~45mp sensor so that fits (for 16:9). 4k60 already exists in the 1DXiii so the digic8 can handle the bandwidth. 4k30 (maybe 60) could be uncropped (oversampled). 4k120 may be cropped. It would be unlikely that dual pixel AF is possible for 8K but people using it would normally manually focus. The initial rumour had 8k30 raw (no oversampling) which makes some sense for external recording as the requirements for large CXExpress cards would be very expensive. Managing heat will be the challenge
1DXiii only has 20mp sensor so it can't do 8k by definition. 4k120 is another question though (firmware upgrade?)
Canon has limited their video capability for the EOS R/RP but it is likely that processing power/bandwidth was the limitation. The cinema range has a different form factor and the R5 wouldn't compete on that basis but would be a great B cam.
Canon needs to lead and the R5 will leapfrog the competition in the mirrorless segment but the price is a big question mark. Let's hope the rumours are accurate... it can only be good for the industry and Canon in general :-)