All plugins do except of they have a live mode (but technically still induce latency, it is just lowered, some of them being able to introduce only a few samples latency).
You shouldn't be bothered by 8ms latency, I don't say you can't notice it but it's officially less than usually accepted for live playing. Also, if you take the speed of sound, it is equivalent to being 2.4 meters in front of your amp (maybe less because I didn't include the slight latency that might be caused by your amp itself depending on its design, although I don't think a simple head would induce that much latency since electricity travels at an electromagnetic wave speed). So when you stand in a rehearsal room, you have more than 8ms latency, easily. Hence why I think it's psychological to be bothered by such a low latency.
And you can use pod farm with any interface as long as you own the plugin version, that you can load in your vst, instead of just the software you record through as if it was your amp.
If you don't want to use both its input or soundcard, I think the line6 product is not worth it. It has mediocre (compared to semi pro or pro gear) converters and DI input. If you are using it only as a soundcard you would be better with as said previously a little interface like the baby face, a Duet, a profire, something like that with 1 or 2 sets of line-mic input, and a dedicated DI box. Not that you can't have a good tone out of your line 6 input, but you are limiting its qualities. I was blown away the first time I used my DI box, the lowend of my guitar DIs was clearer. The other thing is that the dedicated interface would have better DA converters too and if you plug in a pair of good headphones you will hear a difference immediately. My Duet kills my profire 2626 on this level which is already a decent interface (but for the same price it has to offer 4 times more inputs which explains the difference), so I don't even imagine how much more precise It is than a line 6 output ! It's not enough to be a good producer, and Erik has done great tracks out of his line6 interface, but it does make a difference and the investment is minimal.