In general, Rds On (Max) @ Id, Vgs, are these the values I should look at when choosing fets? What kind of values should there be? Is it better to have rds ohm value as low as possible? What else should I look at when choosing fets?
Yes, those are usually the most important parameters to consider, along with ensuring that the absolute maximum Vds rating is higher than the voltage you are switching. When switching an unclamped inductive load, the avalanche rating is important too.
Rds(on) needs to be low enough so that the voltage drop is low enough for the application (e.g. for switching LEDs from a 5v supply I would aim for not more than 0.3v) and so that the power dissipated in the FET is sufficiently low that you do not need any heatsinking beyond what you are prepared to provide. The FET you referred to has Rds(on) max of 43 milliohms at logic level drive and up to 6A Ids, so if you do the sums, you will find that it’s already much better than you need.