Use a screwdriver to remove the plastic step plate from the door sill. Then unscrew the one screw on the front (towards the engine) that holds the panel for the kick panel area. Then you can take it off. It took a while, but after removing the door panel, I fished a wire through the stock rubber looming, it should fish out to the kick panel area that's now exposed. This is what most people do. What did you do on the passenger side?
You shouldn't wire the remote to the battery, you want the amps to fire up when the radio is on, so you want to connect it to the remote line lead of your radio (usually a blue wire). If you don't have one, then you can always run a wire from the battery, but put a switch inn between, you don't want your amps on all day to kill your battery. In this case, it'd be best to also use a relay if you wanted.
You could run 2 separate power wires to each amp, but "splitting" the 4 guage wire should suffice, depending on the power output of your amps. When you split the power from the 4 guage wire, besides putting a fuse in at the battery for the 4 guage wire, you need to put fuses in for each of the smaller wires that will split from your main power. These are referred to as distribution blocks, and you usually want a fused distribution block. They totally range in price, but you can get an inexpensive one at Radio Shack that'll accept a 4 guage wire and can split to 8 guage. For most of these blocks, there really isn't much of a difference, so go with what you want. Buying one over $50 like I did is a waste (I picked it up and didn't look at the price, and was too embarrassed to tell the cashier it was too expensive). Though some boast more than others, really, they're all going through the same tiny fuse, so that's the bottleneck regardless of which fuse block you choose. At cheapest they run like $10, at most above $75.
Drop more info on the amps and you can get more help.
Good luck,
Jon