I have a 1974 Ensenada 20 that I have refitted extensively. I sail inland and it is a lightly-built boat. So far as I know the sink merely emptied into a bucket below - I have replaced my interior and have redone this somewhat. The 1/8" rigging is standard (and should be inspected if it has been used in salt water). There was no flotation in mine - I've added it under the bow V-berth. There was a spinnaker available at time of purchase as well - you could have one made or find something with similar measurements used, but it wasn't a huge kite.
There is a good web page on the boat (not mine) which this site will not let me post for some reason - google "anungoday" and it'll be first.
The biggest problem you'll have in the short term is leakage around the keel cable tube due to flexing of the hull. My solution was to glass a plate on the underside of the sole and join that to the keel indentation via a plywood fitting and it has worked well for some time.
You'll find her to be a good little sailor (with a *huge* PRHF rating if you're a racer) but nothing compared to the sturdy nordic boats that I've seen. With properly trimmed sails (and being sure to assemble the rudder correctly) she sails very nicely although the trailer is in bad shape.