Question about rail from Geneva to Interlaken

Hello there,
I ll be going to swiss on the 28th of May
and we will be entering Switzerland from Paris reaching Geneva
my trip will be roughly like
Day 1
Geneva -- Chexbres Village (using route passby Lausanne to drop my luggage)
Rivaz -- Spiez (using route passby Lausanne to collect my luggage)
Spiez -- Interlaken -- lauterbrunnen
Q1.Can i purchase my ticket from Rivaz directly to Lauterbrunnen and stop by Spiez for a stop of 1 - 2 hours? which one is better a combine ticket or separate ticket.
Day 2
Jungfrau
Day 3
Lauterbrunnen -- Luzern
Luzern -- Bellinzona
Bellinzona -- Locarno
Day 4
Locarno -- Bellinzona
Bellinzona -- Venesia
Q2,.As Bellinzona -- Locarno route i have purchase in day 3, can i reuse it on day 4 just in case i need it to get back to hotel?
Q3.All the trip above i m planning to use it with swiss half fare card as it looks cheaper, is there anywhere to double confirm it?
Q4. i have purchase ticket from lyon de gare to Geneva , and ticket from Bellinzona to Locarno online, and i read somewhere saying that the train ticket can claim for VAT. is it true? if so how can i claim it? as i didnt register under SBB user. Do i need to keep my printed copy as proof?
Q5. i notice that there is machine selling train ticket on the station? can i purchase it using my credit card? as i m aware, the credit card i m holding doesnt have PIN, only require to sign during swiping my credit card.

Thanks

Hi
I live in switzerland and use the train to get to work so
Q1 Yes, you can by a ticket in the machine at Rivaz, it is better to buy a straight through ticket. You are allowed to break your journey during the day of travel.
Q2 No, a swiss ticket is only valid for the day of travel.
Q3 The swiss half fare card would be valid, just specify you have it when buying the ticket (even in the machine) . You will be asked to produce it on the train with the ricket though by the ticket inspector.
Q4 Dont know
Q5 The machines on the station definitely take credit cards, I am not sure about pin less ones though, ask in Geneva station.

Hope this helps