Ok i would do the second bit first.
I would clamp a lump of alu or steel, that was larger than my stock in X. to the table. I would get the positions of the two outside holes and the one on the left and I would bore and tap the alu/steel in these positions. I would then clamp the part on top and do these holes and counterbores and then have a M1 in the code. I would then fix with setscrews and then remove the clamps and machine the hole and the outside.
 I would then clamp something along the edge and one end to give me a straight edge, unbolt the part and flip and hold with the left hand screw and a clamp on the other end. I would then remove the straight edges and machine the slot.
 If that doesn't get you within 0.01 or 0.02mm then you have done something wrong

Hood

Interesting, here's my latest crib sheet for the bottom part....

Rough-clamp part and align long edge,
Drill two 12mm holes - one in small hole location and one in centre of big bore,
Machine the counterbores.

Flip over to front side, realign the long edge and bolt down on some spacers thru the two 12mm holes into tee-slots,
Drill the three holes,
Mill the centre slot,
Mill the profile,
fit clamps outside of machining area and remove the two bolts,
mill the big bore
mill the small bore
mill the slot

In my mind it should work, I have kept the same work origin, the part was aligned each time accurately, no sub plate was needed just a couple of scraps.

Hmm, knowledge gap biting...

I can't figure out ho to remove the waste from the profile

I can contour it which would slot all the way round but i was thinking to machine the corners off then run round the whole part, trouble is, the slot in the drawing means it wants to machine the big bore at the same time as its a common path, this won't work.

Anyone got Fusion 360 knowledge?

Just turn off table display.
I didn't read the whole thread, but this should make the display issue better?

Thats better, thanks.

Is there a way to toggle that while in the 2010 screen set?

I couldn't find one so had to load the 1024 set then toggle it and then reload the 2010

You can do it from Config > Toolpath

Got it, thanks

Any chance someone could scan through the code below please, Mach is telling me the Z limits are +30 to -30 but i cant see why - the tool limits in the first few lines are correct and reflect the settings in CAM but i don't know where its getting -30 from??

Can't look right now, but is that you're current location?

Sorry cant help with your CAM, in BobCad you can add a line or dotted line to span gaps etc but what your cam does I have no idea.

Anyway your z-30, likely you have not homed and the machine coords zero is 30mm below where the G54 zero is.
Also not supposed to have a G90 or G91 on the same line as a G28.

Hood