'Noobish' questions as I look to upgrade my car audio audio.

[DkY in Vcr]

Hey all, really hoping you guys can help me with some questions this 'old dog' has.
I'm looking to add a JL Audio XD400.4 amp to power a set of C2-650 6.5" separates, then bridge the other two channels to a sub (to be determined later). I'm fine running the stock rears off the stock deck.

Questions:
1] How do I best remove the stock amp (& wiring) in the trunk? The power wiring in particular concerns me... I'd prefer not to come back to a smoking car. . I'll put the new amp in the same spot.
2] I picked up a line out converter for inputting into the amp. The JL amp manual says I don't need a full 'line out converter', just a 'speaker level to RCA' connector? It actually says the LOC could add unnecessary noise. I'm not sure what those look like or where to get one (I'm in Vancouver, Canada).

Sorry if these questions seem fairly obvious; I tried searching & couldn't get these answered... though I did find out a ton of other good info.
Any advice is greatly appreciated!