Welcome to FT. Please stick around, some new insights are always good, just bear in the mind the humour is fairly warped at the best of times.

The BA - IB computer link is a well known disaster area. Get your seating options via the Finnair website, that normally works better. I've never succeeded in getting a IB seat via BA.com

For the tier points, I would need to know the precise routing, but - for example, if you have a new leg LHR to MAD that would indeed be 40 tier points each way. For us country bumpkins we get another 40 tier points just getting to LHR (on a BA flight with an IB code), followed by another 40 from LHR to MAD, plus 120 to SCL or whereever. The hilarious thing is despite the stonking TP situation I get far fewer miles than if fliying on the cheapest possible BA ticket.

The TP from Iberia count towards BAEC, so you should be well over as a result of this exercise.

The business class seat is not at good as BA's - it is fully flat, higher up than BAs but somehow not quite as comfortable. The food is better (for what it is worth) but the service from staff not as good despite seemingly having vastly more staff than BA in the same class. It's cheaper for a reason.

One point to note: If you arrive into MAD from LHR on an Iberia metal plane then they will probably offer a bus link to the satellite terminal from the rear doors. Take it to avoid a train trip and various into/out of Schengen controls.