Juni,
As many have said, the E30+ is a great boat, much better designed and built than either
a Catalina 30 or an O'day, both of which I've sailed.
None of the problems you list above are insurmountable, so to start on a few:
The nav equipment not working could be as simple as a loose or corroded connection. If you know how to use a Multi meter you can problem solve along the wiring. Raymarine has a very helpful tech department which you may find useful.
The pressure water issue could be as simple as checking to see if the pump will come on. If not, is there voltage at the pump, a broken fuse, loose connection, plugged vent hose, enough water in the tank? If necessary, a new water pump is less than $200.
If your boat has a stuffing box rather than a packless shaft seal, it should drip a bit while the engine is running to keep the shaft from overheating in the stuffing box, but it should not drip with the engine off. As long as there is a pick up strainer somewhere in the bilge (original was attached to a red hose) having the bilge pump located separately in the quarter berth in a porthole is good, as it keeps wires and pump out of the wet bilge. These pumps can last 20 years, and if needed can be bought for about $150.
For your ice box/refrigeration, you can buy icebox conversion kits (mine is a Norcold, which has now worked well for 14 years, but there are also other brands), but they do cost about $1,000 (still much cheaper than your NYC rent).
Your lack of access to the water tanks can also be readily solved. The main tank is under the starboard settee, and I if you have the optional tank, it's under the large locker under the v berth cushions, but you have to empty that locker, remove the screws holding the floor piece in place, lift it out and you'll see the tank. Cut a hole in the top of the tanks with a jig saw and cover the hole with a plastic port (about $10 each at a chandlery). The port comes with a frame with screw holes, so just caulk the rim with a good sealant and screw it down. The port unscrews from the frame with a simple twist when you want to check tank level or clean the tank.
Most of us have done these and other modifications and repairs over the years, and can provide guidance--it's part of boat ownership.
You have a well built boat and an engine with a good reputation. If you can do the suggested work, or get help from a good friend, or if necessary hire a pro (but check around to ensure you get someone reputable), you will have a boat that looks great, sails well and you'll gradually learn her systems and parts.
Finally, before we bought our 1984 E30+, she had been owned by a lady with a cat who lived aboard comfortably for two years.

Frank