Your 26-footer will be a fair-weather boat.

Depending on the weather, you can use it almost anywhere. Running
through the Golden Gate and beyond will require proper conditions,
(with wind and current both considered), and you would be well advised
to stay ready to scoot back into the bay if those conditions begin to
deteriorate.

If you're looking for a boat that can plow safely and comfortably
through truly snarly conditions, most 26-footers, including the one
you're looking at, are not designed for the task.

Yes, get a survey.
There will be a list of things wrong with any used boat of that age.
Few surveys show that a boat is "perfect", and when a survey does come
back without a single exception that might indicate more about the
surveyor than the boat. The trick isn't to find a boat that is free of
defects, but rather to find one that has the defects you will be
comfortable tackling from both a mechanical and financial standpoint.

You marine head shouldn't really have a smell. The leading causes of
stinking waste systems are plugged or inadequate holding tank
ventilation and deteriorated hoses. Some people yank the holding tank,
leave the hoses, and then wonder why the boat still stinks.