An espresso machine generally refers to a machine that has a group handle and basket that is loaded with ground coffee and attached to the machine. Water is then pumped through the coffee and into a cup. These machines generally make the best coffee although there is definitely a lot more skill and patience required to get the best from them.
If you are going to invest in an espresso machine then you should also invest in a decent grinder. If you are this serious about your coffee then freshly roasted and freshly ground beans is the only way to go.
As for maintenance, they are a lot less complicated than an automatic machine and there is less to go wrong. Take the group handle off and flush the group head straight after making your coffee. This prevents all the vapours and oils from the hot, wet coffee grounds from finding their way back up into the group head and blocking things up. Wipe the steam wand straight away, before the milk has time to harden on it and purge it to get any milk residue out of the small steam holes
Regular descaling is a necessity to keep your machine running at it's best