The flights between Porto and Madrid would be in Iberia's short haul business class product, and between Madrid and Sao Paulo depending on your luck it will be an A350 which means something similar to this (you can see my seat review here):
or in a Boeing 777 later in the year, if you are very lucky,
As this is a Schengen to non-Schengen transfer, your flight would arrive from Porto at Madrid T4 and the LATAM flight departs at T4S which requires clearing Schengen border control. LATAM uses Iberia's Velazquez lounge which has pretty stunning views over the apron.
Availability appears to be a lot better towards the latter part of the year, though this fare is actually composed of two one way fares, so there is no minimum stay requirement and, oddly, no advanced purchase requirements either. If you choose to credit this fare to British Airways Executive club it would yield 360 Tier Points, which is confirmed by the official Tier Point Calculator.