Thank You for your advices JAZZCNC. Much appreciated.

As for rails, I think to use MGN12 rails with MGN12H carriages for Z and X axis. For Y axis HGR15 with HGW15CA (or other type, depending on final design) carriages.

I have concerns if MGN12 with MGN12H will be enough for Z and X axis ? (even though I have seen those used in small cnc machines).

I really liked the CSMIO/IP-M 4-axis Ethernet Motion Controller, but in specs it shows that the spindle axis is not supported ?

I have ordered 800w water cooled spindle from aliexpress (the size was the buying factor - 158 mm fits nicely in my design) I expect this will be good enough for small aluminium works ? :)

As for stepper drives, I will go with DM556 (or if needed - AM882). But what about steppers ? What torque I would need? (I plan to use pulleys and make 2:1 gearing or just leave it 1:1). The size is important too - smaller steppers are better for my design :)

Do I need closed loop steppers and drivers ? (are they worth the money ? )