New Member, site to buy components?

Go for it.

Those components values should be fine for your low-pass filter, although I would recommend a higher guage for the inductor (like 14 or at least 16 AWG.)  For the high-pass portion, you'll want a 5.9uF cap and a 0.75mH inductor, and since you're looking at second order don't forget to reverse the electrical polarity of the tweeter.

-edit- when choosing component values, you are generally OK within +/-10% of theoretical.

I haven't followed this entire thread and don't know what all you've accomplished here, but I could add a couple comments.  The sensitivity you described above...is that correct?  The woofer is higher sensitivity than the tweeter?

And have you taken a look at Speaker Workshop?  It would help you put the crossover together with more clarity of the result.

DYohn was kind enough to give me much the same advice he gave you in crossover construction.  Some of what you learn though is going to be through working it up with the ability to make changes later.  Here's three examples of crossovers I've built through the learning process:

On the above, I tried to conform to premade PCB boards.  I found it difficult and confusing, and this shows that I didn't grasp the concept of coil alignments.  The pre-printed layout of circles for the coils added to my confusion.  Two of these coils have to be stood on end at 90 degree angles.

With suggestions made by DYohn, I started to get the concept of using other materials for the board.  This made the process much easier as I could put the crossover network together as it looked in the Speaker Workshop schematic.  You see here that I still didn't understand coil layout and it was pointed out that I had two coils together in the same plane.  For this layout, I used his recommendation of high grade 16 ga. silver-coated connecting wire.  I found it to be wonderful for soldering.

By the time I built this one i had enough experience and foresight to put it together without the sleepless nights.  For this, I used the fiberboard you see on the back of clipboards, cut to size.  Used hot glue to secure the components.  I used the Speaker Workshop schematic and re-drew it onto a paper the size of the actual board.  Then I just copied what I drew onto the real board.

There will always be the availability of tweaking your crossover, so don't worry so much that it is perfect from the get-go.  Sometimes you just can't know, such as decibel loudness difference between the mid and tweeter.  You have to be able to allow yourself to make some changes.  Already, after listening to the speakers that this last crossover and its twin is in, I will be trying out a different pair of resistors for the tweeter.  The db drop will be barely 1 db, but I will try higher grade resistors as well.  That's a very subtle change in the overall sound but it's a privilege you are afforded when you are building your own passives

With what you described above insofar as relative sensitivity of the drivers, there is no need to put in padding on the tweeter as it is already less sensitive than the mid.  If you haven't purchased the tweeters yet, consider using a 6 or 4 ohm version, or match the mid in that regard.  Your final impedance of the crossover should be no lower than 4 to 6 ohms for quality car audio output from your amplifier.  It doesn't  make sense to use quality components and build it yourself only to run your amplifier at its dirtiest output.