I took on project car, using all Eastwood projects up to now.
Media blasted car, thoroughly cleaned, de-greased etc, sprayed with 2k epoxy primer all over. Dents straightened any filler applied on bare metal or epoxy, epoxy sprayed over any bare spots and then 2k spray polyester, grey. Then 2k urethane primer sealer, black, mostly sprayed with 15% reducer. All sanding has been done by hand, dry.
For a base / clear I am intending to use Sherwin Williams Ultra 7000 base and Finish1 FC770 clear. The color is dark blue, solid - not metallic or pearl etc.
I am working through each panel and sanding each panel with dry 600 grit so that when I do go to purchase the base / clear, all panels will be initially prepped.

1. I am intending to scuff each panel before spraying base and clear, with a grey Scotch pad. I will be cleaning and degreasing each panel. Is this ok? Is the dry 600 grit too fine?

2. Some interior panel have a grain effect embossed in them, they have been sprayed with just 2k Epoxy to keep the effect. I was intending to scuff these with a Scotch pad, is that ok, red or grey pad?

3. I have many additional panels, headlamp shells, hinges etc, with lots of nocks and crannies. During the prep with the dry 600 grit I exposed the grey 2k polyester or bare metal underneath. What may be the issues with leaving those spots and spraying with the base/ clear over the top? These are very small, maybe pin head or x2 pin heads.

A link to the SW Ultra 7000 specs.. https://apps.sherwin-automotive.com/media/pds/English/AS1382.pdf

600 grit is perfect to paint over, you don't need to go any finer.
A red scuff pad is just a bit to coarse of a grit to safely paint over,
you may get by with a non metallic paint but a gray pad is a lot safer
and plenty good to paint over. Just make sure it thoroughly scuffed
and clean.

Great thank you much appreciated.

Will the base paint show a step or ridge if I spray over the black 2k urethane which has small edges where the grey 2k poly is showing through? What about exposed metal?
I am a bit concerned that more may be exposed when I prep the panel with the grey pad before applying the base. Is this why shops spray a sealer just before the base / clear?

I am also wondering how I would go about masking different stages of the base/clear. For example the steel doors on the inside have a mottled effect and I was think of spraying them the same blue color as the exterior but with a semi-gloss clear. I was thinking of spraying all the semi-gloss clear parts first but I was wondering how long I need to wait before I can mask those parts up and spray the exterior of the doors etc before I can then spray the base / gloss clear?
Is there a preferred tape that is used in this situation? I am using 3m 233+ automotive masking tape, I also bought some 3m precision tape 06529 and I have 3m precision poly tape 36354, are any of these ok?

Here is a picture of where the 2k urethane was rubbed through and exposed the 2k polyester primer. If I leave as is will this show through in the darkish blue base paint?

I also have areas where 2k epoxy was sprayed before the 2k urethane, both are black. Will these also show through the base where the 2k epoxy is exposed?