TheRealZap

no reason at all to install gearbox or pod farm 1, just install monkey, get the drivers and pod farm 2.5+ (latest) then use the license manager that installs with monkey to authorize the UX1

service centers are independent and set their own prices out of warranty.
i believe that full compass has the switch, but i dont know the link.

check the control panel there should be a line6 audio/midi control panel.
you can define what the meters do here.
they may be set to monitor a different input or something.

the redface toneports did not come with a plugin license.
it sounds like somewhere along the way you updated the toneport back to default and removed the previous owners paid license.
if pod farm 1 standard works standalone... then it's working correctly.

hold down left key while powering on.

none of the amp models have been changed since the release of the HD500x.
the update was primarily L6LINK enhancements.

you may need a newer version of monkey, or updated drivers... both of which you can get here: http://line6.com/software/

pod farm replaced gearbox plugin.
use monkey to download pod farm, it will unlock the plugin version for you for version 1 for sure... version 2.x maybe (depends on when it was originally registered by original owner)

Sorry, that won't work.

http://www.youtube.com/watch?v=caj-z5pPZo8

no... tight loose etc... is the amp topology without the pre-amp setting... 
(meaning selecting those options is different than selecting I-IV on the amp itself)
DT customizer basically turns it into an amp factory.. you use a modeled pre-amp and you can setup the amp characteristics how ever you want.
 

yeah you wouldnt hear anything on the app... but if you can see it... you might be able to dial in the settings to your pod...
 
which is kind of useful since you previously couldnt view x-series tones in an "offline" manner (offline as in hardware unplugged)
 

i know you can use the xlr to record anything really. i don't think that it keeps your loops separate though.
sounds like you need one of those multitrack recorders and a footswitch honestly....
you could have fun with the looper, i just don't think you'd find it to be an adequate recording solution based on your questions.

standard cat5/cat6 cable: http://line6.com/support/page/kb/_/legacy-products/effects-and-controllers/floorboard-fb4-fbv4/line-6-floorboard-and-fb4-faq-r507

the actual breakout of the FBV port is pretty much digital and midi....
so adapting it just for an expression pedal would likely require a midi expression pedal and not an analog one.
the controller, converts to midi before sending over fbv cable...
in short unless you are an engineer with loads of time and determination... 
i don't think what you want is feasible... (although obviously nothing is impossible with the right knowledge... but worth doing... another thing entirely)
 
you can use a non-proprietary midi foot controller, if you wanted to make the effort to get that setup... still won't likely accept your current pedal though.

it's not an audio interface... if you look over the forums you will find many unhappy users that tried to do this.. with supported drivers...
you're doing it the best way right now.

No way that i'm aware of.

just looked, it says that the FBV2 and FBV4 pedals are the only ones supported.
for the most part i'd say that your friend was correct and that those additional features will not work on that amp.

the warranty starts on the date of your original receipt.
you might do yourself a favor and start using the new one, and make your old one the backup... that way if problems arise you can use the warranty.

the looper is simply mono... that's why. not likely to change, as it may reduce the time available for the looper, or put a higher strain on processing capabilities.

customizer will not even install on the old ipad, but touchosc works.

yeah i got in on the same deal... was 35$ to upgrade when PF2 came out. 
unfortunately the official rules say that you can only transfer full price licenses...
honestly i'd just keep it! (don't think it would add to the used price anyway)
because pod farm 2 (2.5 and later free upgrade) works independent of hardware... so you can keep it even if you get another interface.
(the model packs however are tied to the x3 so you'd be keeping "standard" which is more amps and effects than free at least)
just tell the new owners to use pod farm 1... they still get all the models etc... its not that much of a downgrade...
you may be able to call support and ask for a transfer exception if you really want to pass it along.. i can't say if they'd grant it... but worth asking.

I assumed you were already aware of that, but RCA to 1/4" mono TS connectors are pretty common....
if you wanted certainty you can get this as well: http://www.amazon.com/Behringer-PP400-Ultra-Compact-Phono-Preamp/dp/B000H2BC4E/ref=cm_srch_tsr_rtr
(or a similar phono preamp)
you'd still need the above adapters, but that will get you in at line level.

yes to everything... although i do think you'd probably be served just as well with the pod hd desktop.
summary:
1. yes
2. yes
3. yes
4. yes (subjective... but the modeling is newer technology and this is my opinion)

you do get 32 presets with the FBV shortboard according to the manual:
 
connect a Line 6 FBV Shortboard controller  for channel switching, effects on/off control, wah/volume pedals, access to 32 more channel memories, a  chromatic tuner, and tap tempo for delays.   ----- manual here: http://l6c.scdn.line6.net/data/6/0a060b316ac34f059357c410f/application/pdf/Spider%20II%20User%20Manual.pdf