New home already has a tub - Help!

We just bought a home that has a Coast Spas tub in it. From googling the serial number, it says it is a “A-W140V Wellness Swimspa Wellness 1400 Low Profile”. Haven’t ever owned a tub or pool before and can’t find the owner’s manual online, so trying to organize some notes on how I should plan to care for this thing to use it regularly. Here are my current notes and/or questions:

1. Drain and refill: do I need a pump? Or do people attach a garden hose to some outlet and just let it flow out?

2. Filters: I’m still trying to locate mine, but is rinsing them out with water enough? Or how often are you actually replacing with new ones?

3. Water quality: i’ve read about balancing pH and chlorine levels and some other things; how many products are we talking about? Any overlap? For example, should I plan on buying pH up, pH down and chlorine/bromine tablets? Or more than that?

4. What is “shocking”?

5. Other cleaning agents I need to buy for when I drain and refill the tub to clean out jets and stuff?

Any other regular use items or procedures I should read up on / purchase? Thanks in advance!