vmoncebaiz

For the functionality, the Spider V + FBV should be very similar to the Pod XT Live. Bank Up/Down and Preset A-D are in the same spot.  you will have a little more flexibility since you can assign 3 FX to different foot-switches (they were fixed positions in Pod XT).  The PodHD500x would be even more flexible and offer 8 assignable stomps.  It also offers more flexibility in your signal chain and can run 2 amps at a time.
 
For the sounds, The Spider V has a similar model set to the Pod XT, but also has the speaker built in (so it might be more convenient as an all-in-one).  The HD500x is a newer range of amps and effects (HD amps, cabs and FX)   There will of course be some similarities in what the models are based on. The only model set newer than PodHD, that is found in Helix family products.

With any block in your signal chain (in your case, the delay), you select it, and press the "Action" button grab it.  Then, press down on the joystick and it will move to a second parallel path.  Using the same process, you can move the split and merge points around too to have certain effects interacting with others as you please.

I do it by matching to the volume of the factory patches.  I start with the Helix volume at 50%.  Then I set up the tone the way I want it to sound first,  and then I compare the overall volume to a factory patch. I use a free SPL meter app on my phone and my ears just to make it so my patches and the factory ones are going to blow the doors off if I switch back and forth.
 
Then there are a number of ways to adjust the volume of the patch without affecting your tone.
 
1) channel volume on the amp block
2) level on the cab block
3) level on the output block (or a merge point if you run parallel paths back together)
4) add in a "gain" block at the end of your signal chain (found in the volume/pan section of effects)
 
Hope that helps a bit.