Questions on 35d SCR/DPF/EGR delete

[e39_touring]

When we got our 35d a few years back, we knew a trouble point on the diesels can be the emissions equipment and figured we'd do the delete when the time came. In fact, BMW also recognized this and extended the warranty to 10yrs/120k miles, and we had the active tank replaced under that warranty a year or so ago.

Well, now the EGR cooler (the device on the front of the motor by the head) has a broken spring, and all extended warranties are expired.

A few questions for those who've been down this path:

1) Is that EGR cooler spring replaceable without replacing the whole unit? (I couldn't find anything indicating it is)

2) Can I do the tune to remove SCR/DPF/EGR from the ecu but leave the equipment intact for now without adverse effects? I would block off EGR now but leave the other stuff in place for the time being, but I'd be concerned that the SCR will plug up or something like that without the diagnostics in place any longer.

3) Is the swirl flaps delete worth doing as well?

4) Would a stage 1 tune be worthwhile and will it negatively impact reliability?

Thanks in advance for any pointers!