I am thinking of applying for a priority pass (PP) for my upcoming trip Bne-Calgary return.

I am thinking of applying for a priority pass (PP) for my upcoming trip Bne-Calgary return. This is because AA have suddenly changed all their flight schedules, making me wait for many hours at LAX, on both outbound and return trips.

Outbound: Arr 6AM at TB, wait 7hr for connecting flight dep from T4. With a PP, can I access KAL lounge at TB on arrival before checkin at T4? (no lounge at T4 accessible to PP.) Is it true that with a PP, you can only access a lounge at your departure terminal, after immigration, with your boarding pass?

Return: Arr LAX/T2 12 midday, 11 hrs wait, Dep LAX/TB 11:30PM. With a PP, can I only access KAL at TB?

Does this mean, with a PP, for my upcoming trip, the only time I can use PP is at TB on my return journey?

Appreciate any tips I can get to help me making decision. One thing I know for sure: will not fly with AA again. Thank you

Don't know too much about the PP lounges.  However by the time you clear customs you could leave the terminal and get a taxi to Santa Monica and hang out down there for a while.  I believe some LAX hotels also offer day rooms so you could grab one for a few hours.  I've had a similar stop to yourself and (12 hours) and hired a car for the afternoon and had a day in LA.  Much more fun than loitering at an airport.

There is also the option of the 30 day Admirals Club Pass.  Might be better value if it is just for this trip.

Have you considered getting a Diners Card which gives  access  to lounges in various parts of the World

At LAX  in the TBIT   i used the Skyteam  [KAL] Lounge for free.

I got a fee free Diners Club card through Citibank years ago .

Access to non departure many depend on the TSA you strike. Found link http://onemileatatime.boardingarea.com/2014/12/11/the-trick-to-using-the-best-lounges-at-lax/ which suggests you can access any terminal at LAX. 

Your in LA, Go out and enjoy the day

As 11sjw said Santa Monica is one of the closest areas you could relax and enjoy.

I do have a prority pass card which I get from my Amex card but wouldn't go and buy one as its not great value for a once off visit

Also note - The KAL Lounge is around busy times (Holiday periods) not accepting Prority pass cards.

Also 11sjw noted that you can buy a 30 day AA club pass for US$99 (from memory) or a pass once off at the door for US$50

I would not want to spend a whole day at the KAL, AA or really any lounge at TBIT unless its the *A or QF Lounge at a push.

A quick google search with something like "los angeles things to do near airport" will come up with some great results and you will have a really fun time.

Final thing, In the US you need a valid boarding pass to access the airside area of the terminal so if you don't have your boarding pass cause checkin has not opened then you can't access the secure area of TBIT and thats where the KAL Lounge is.

You most likely will be refused entry to the KAL lounge using Priority Pass during this holiday period especially during the day hours where several skyteam flights depart. Its noted in the Priority Pass terms that entry is subject to capacity restrictions. 

Personally, you couldn't pay me to stay at the KAL lounge for longer than an hour. It is nothing compared to the Star Alliance Lounge and QF Lounge. Just a quick search on the web will reveal so many horrible reviews of the lounge and those are even by people getting complimentary access for flying business etc. 

Its worth noting that the majority of people using Priority Pass received complimentary membership through their credit card companies. I have had complimentary Priority Pass for the past 10 years through my AMEX platinum back to the days when the Virgin Australia lounges were accepting PP members. Also, most of the domestic lounges in LAX offer day passes, such as Delta, Alaska, and AA. 

If you really want to stay in the airport, then you could try your luck with the KAL lounge, but otherwise you could use Priority Pass at the Air Canada Lounge (2), Virgin America Lounge (3), Alaska Airlines Lounge (4). It's just not a simple quick walk between lounges.

If I were you, I'd save that money for a fun outing to Venice/ Marina Del Rey/ Manhattan Beach/ Santa Monica etc. You could have a great meal at so many restaurants on offer and a fun experience overall.