Some of your points addressed in no particular order:
- FPL required for flight in CAS (which is most likely since there are large areas of Class D above 1000 AGL, transits never a problem)
- Peak times (certainly July and August, not sure about Easter) certain airports do not accept VFR traffic on certain days - check the AD Notams
- No night flying unless you have IR and short night bimbles are a pain because departures from certain airports are via the SID which takes you miles from where you may wish to explore
- VFR departure and joining usually via a reporting point N/E/S/W
- Radar based FIS - No need for the UK style hello/heading/altitude/next waypoint/ETA - they have your flightstrip and can see you on radar
- ATC nowhere near as slick as in the UK or Germany
- Charts etc can be downloaded from
www.aena.es (registration required) or the Eurocontrol website
- Landing and parking fees are very reasonable