Please advice on my 12days honey trip

Hi all, please advice on my plan as below:

5 June Arrive Zurich at 9:00, will go to Zermatt by train on the same day
6 June Stay at Zermatt
7 June Stay at Zermatt
8 June Go to Bern by train
9 June Stay at Bern
10 June Go to Grindelwald by driving (renting car)
11 June visit jungfraujoch by cableways
12 June stay at Grindelwald
13 June visit Vevy (renting car)
14 June visit Luasanne (renting car)
15 June go to Zurich (renting car)
16 June visit St gallen, stay at zurich (renting car)
17 June back to Hong Kong

Any comments? Should I take a Half fare card or what?
As a return ticket is included, can I use it for : 1. From Zurich to Zermatt, 2. From Zermatt to Bern?

Thanks in advance for your help

I agree with Annika - who needs a car in Switzerland? The train/bus/boat system is awesome, and you don't have to struggle with finding and (importantly) paying for parking. I have spent 7 weeks in Switzerland at various times over the past 2 years and have relied on my SwissPass exclusively. I've visited 26 different towns/villages, either via boat, train or bus, and it's been carefree and lovely. Of course, I pack extremely lightly (Rick Steves' website had fabulous advice on packing light) so I don't have to lug large luggage around when I do so. Download the SBB app to your smart phone and you'll be able to find the fastest or most scenic route between any points you can imagine. And if you don't speak German/French/Italian, driving can be a real challenge as the signs aren't in any other languages, and the symbols aren't universal (for example, the symbol for "not" in the US is not the one used for "not" in Switzerland, as in "not" a route for pedestrians... I wish you wonderful travels, regardless of how you choose to travel!

Thanks for the useful information, I will think it twice now