Have you actually heard any of these speakers in a car? Speakers sound completely different on a sound board to a car. It sounds to me like you've read a few forums which is a good starting point, (Mobile Electronics Australia is prob one of, if not the best Aussie car audio forum. Nothing compares to actually hearing the speakers you are wanting to spend your hard earned on, in an actual car. Ideally powered by an amp.
Is there a reason you want to go with JL Audio for your entire set up? Mixing and matching will yield you better results in the end. Think of it this way, if JB Hifi sell it, look elsewhere

Don't get me wrong, JL do make some nice gear, there is just a LOT better out there for the $$$. Look at mid spec'd CDT and Crescendo as a starting point.
You haven't mentioned anything about sound deadening which is almost a must for Subaru's and their inherently flimsy doors.
Will you be installing yourself or having a "pro" do it? If so, you'll need to budget for an install. FHRX Studios and formAUDIO I would suggest in NSW.
As for 5ch amps, they have come a LONG way and are pretty grunty and can hold their own against a lot of multi amp installs. However, if the amp dies, your whole system dies. I'd suggest a decent 4ch and a mono for the sub. One thing I will mention that hasn't been covered is; don't worry one for one second about matching RMS values of amps to speakers. Look for an amp that exceeds the recommended RMS values of the speakers you end up buying. This will ensure that the amp doesn't have to be run excessively hard to achieve the same output. And anyway, RMS values provided by manufacturers are pretty meaningless. Just don't go overboard and hook up your new subs to a 240v GPO and you'll be fine.
As for an opinion, you can do a LOT better for the money you are looking to spend. Also, unless you have passengers in the rear seats ALL the time, don't buy rear speakers. They are a waste of money and do nothing for the overall sound. In general, to achieve "best" results, you should be looking at having the sound faded all the way to the front and hence no sound coming out of the rears.
Overall though, you're on the right path, there are probably a few things I have covered in posts like yours so you might want to search some older posts myself and a few other guys have contributed to. Also, don't take my word for a pinch of shit, get out there and find out what sounds best to you. In years gone by it was nothing for me to spend $1,500 on a set of splits only to get sick of them in a few weeks, sell them off at a half of what I bought them for and go out and spend another $1,500+ on another set of splits. It is a habit that can quickly get you into junkie territory LOL. Now, I'm driving around in a Sherpa with a stereo made up of second hand gear that anyone that was serious about car audio would laugh at and also a GenV GT with a stock stereo which sounds worse than my Sherpa LOL. In my Sherpa's defence though, it does have one of the best "imaged" sounds I've heard in a while that doesn't utilise an external processor, size DOES matter and processors are for pussies anyways

However, in the last few weeks and months I have been trialling different bits and pieces in my GT and other installs I have done for people recently and am hoping to get everything together and budgeted for and passed by the minister of internal finance and relations in the coming weeks. So I'm hoping one day soon I will be able to have a thread that rivals andy85's sex on wheels stereo.