A:AnswerYou would need a wiring harness for connecting speakers directly or you can cut off the factory speaker connector and splice the wires directly. You will also need a Nissan bracket adapter to mount to the speaker. This will keep you from having to drill new holes.
A:AnswerA 2 way speaker is one that has a woofer (for lows) and a tweeter (for highs) built onto one frame. It eliminates having to have 2 separate speakers.
A:AnswerThey’re the same size as your stock front speakers, they should fit with no issue. Your front speakers are 6x3/4 and your rear speakers are 6x9.
A:AnswerThey can fit in your front door but you might need a separate bracket to secure them. You could also use self tapping screws but it’d leave a less professional look and if you ever took them out you’d have the extra holes.