I have never replaced a pickup. I've got a strat with 2 pups: a big humbucker at the bridge and a duncan lil' '59 single coil-size humbucker at the bridge.
The 5 way switch creates all these different combos, one coil from each pup, etc-all sound bad to me.
I am replacing the lil '59 at the neck with a regular Duncan strat pup, so it should fit with no problem.
I have no idea what's underneath a strat's pickguard.
Will it be pretty easy to follow the example of the lil' '59 and just install the strat pup the same way, or will the fact that I'm going from bucker to single confuse me. I'm not really worried about running both pups at once. I'm just happy with a bridge and a neck tone.
Any advice would be appreciated.
Iknow how to solder and stuff like that. I just don't really understand how pickups are wired or installed.

I would just replace the switch with a Tele-style 3-way switch. You will have to do some rewiring with the humbucker wires. What kind of 'bucker is it? Different brands have different color coding.

The bucker is a duncan that has green, bare (ground), white, and red wires.
The single is a duncan with a white and black wire.

You need to solder the white and red wires of the humbucker together. The green is your ground and the black is your output to the switch.

The white wire on the single is your output to the switch and the black goes to ground.

Here's a link for the correct way to wire a tele style switch:
http://www.seymourduncan.com/support/wiring-diagrams/sc...ematic=standard_tele

PM me if you need any more help.