For the SoC the ball size is 0.35mm, I don’t typically use paste as it typically butchers the chip due to issues keeping even and consistent pressure on and across the whole stencil, but it would seem the jig you’ve linked to eleviates a lot of these issues as it’s using a magnet to pull the stencil down… Though I will say, I’d question how long it retains it’s magnetism afer a few heat cycles.
as for the other ICs, sorry I’m not sure, as they’re small enough to use paste, I would guess the Ram is the same at 0.35MM (but you could check in the datasheets based on the packages), no idea about the EMMC.