They sell decals, I would put those on.

I would make sure the inserts are flush with the playfield and then install decals.

In regards to the cracks it's hard to tell in a photo. You may just be seeing where the edge of the decal has flaked off. If the crack around the insert is larger than usual I would either replace the inserts or use CA gap filling.

If you're not up to that big a project, just put some static cling vinyl over the area.

I sure wouldn't put a decal over that... the wear isn't bad enough to warrant it, and will change the ball trajectory as it rolls over the edges. (Ask me how I know).

The wear will continue, but in typical home use, shouldn't be that bad, and will take a loooong time to get really bad.

I'd suggest as was previously, make sure the inserts are level with the playfield, and lock them in with CA (superglue) It's been outlined in the pinrepair tapes before, on the IJ one if I recall.

Use a pipette to just place small amounts around the cracks. (touch up with acrylic paint beforehand if desired) Once the cracks are filled.. use a small block and 1000 grit, then 1500, then 2000 and higher sand paper to level the repair. Once done, polish with some Novus 3 then two, and you're done. Shouldn't take more than an hour or two's worth of work, looks way better than a decal, and it will last a really long time if done properly.

My scared stiff spider hole looks factory fresh, and I did the repairs on it over 10 years ago.

Big Decal, I have the individual ones and only rarely does it affect the ball (Slow moving, rapidly spinning). I imagine it's even less of an issue with a larger overlay. Obviously the best way is to level them, paint them, and clear. If I'm going to that extreme I'm just going to wait if/when CPR does a repro playfield.