First build-day. Have been planning for a while, but now it is time to try my ideas.
Connected an i2c 24c02 EEPROM, using A0 as a chip select. Found out that the address is actually NOT based only on A0-A2, but also a hard-coded chip-type specific "magic number". In this case the four MSB are 0b1010 according to datasheet, but it answers at 0b0101 instead using micropython. Oh, well at least it works...
Reading and writing to the chip works, and the use of address-lines as CS works as expected. Hooray!!! :D
Oh, and all the additional components have arrived: SPI-RAM, SPI-EEPROM, SPI-pots, and atmegas with crystals.