<<"1) I will likely go to a number of towns & mountains. I understand that not having the swiss pass would mean I would be paying full fare for all the inner city trains / trams / buses / boat rides I would take as well as the cable cars. How expensive can this get?">>
Parking int main station garage in downtown Luzern is roughly 4 CHF per hour. The garages are often full on weekends. The whole country is geared to using public transport, and cities are working hard to make driving in the cities difficult and expensive.
You would be wise to carefully consider the 30 day 1/2 fare discount card for 120 CHF per person. It will give you substantial discounts on all intra city transport...typically about 50%
in a city, you can purchase any of a confusing array of tickets for local or near local public transport
Tickets are available from machines, but making choices is confusing.
I suggest that in each city you go to the Tourist Info office in the main station or the office of the local transport network (also in the main station), and ask about ticket options.
Here are some rough ideas on costs...sorry, I can't remember the exact amounts.
A single ticket in Zürich good for an hour or a few hours or maybe less on the buses and trams in zone 110 ( the city itself) is about 4.5 CHF. A "short trip ticket" good for less than one hour is about 3 CHF.
A 2nd class 24 hour city card is costs about as much as 4 or 5 or so single tickets. Maybe a bit more. If you add access to more zones near the city, the cost is 3 or so CHF per zone.
There is a so-called 9 o'clock card that give free travel after the 9 AM "end" of the rush hour until midnight... I forget what it costs. Cheaper than the 24 hour "day card."
Luzern has similar costs, and that arrangement is similar to other major cities in Switzerland. Luzern is quite compact...you may be able to walk to everything. Ypu may not need to [ay for local transport.
If you have a Swiss Pass, you ride free.
Three days of 24 hour cards per person could add up to 50 or more CHF, roughly, based on my memory.
Out in the country...or the Berner Oberland, different rules apply.