How far away from the screen will you be sitting? This will assist with determining screen size (Erskine Group may have provided this data). One option (Which I usually recommend) is having a false wall built and use an acoustically transparent screen with the speakers behind the screen positioned at optimal tweeter height.
As far as projectors go, you have several options here. The Epson you mentioned is a solid choice. With your budget I would stick with it and then decide how large your screen will be, but spend no more than $1K or so on the screen.
That said you need to decide if 3D is really something you want. I personally do not feel it is a "gimmick", but it is just my opinion. Have you been to the theater to watch a 3D movie? Did you enjoy it? Your existing Onkyo receiver does not support 3D. So if 3D is something you want, you will need to buy a new receiver that supports 3D. If you don't want 3D then you can keep your receiver and there would be little sense buying the Epson 5010 and you could get a cheaper projector. So you really must answer the 3D question. Personally, I enjoy it. But there is limited content in 3D currently, so most likely less than 10% of your viewing will be 3D depending on your tastes.
Yes, surge protectors are a good idea. I actually recommend installing a whole house surge protector at your breaker box/electrical panel. Talk to your electrician. You won't need to spend much here.
Here are my estimates assuming you want 3D:
For a projector I would recommend:
Epson 5010: $2699
To save some money here I would also consider the BenQ W7000: $2199.
http://www.visualapex.com/BenQ/Projector-Specifications.asp?For-The=W7000
For a screen, I would budget around $1K. But we need to know your screen size and whether you want acoustically transparent or not.
For a receiver I would get a Denon 1712 which supports 7.1 channels and has Audyssey MultiEQ XT ($400):
http://www.amazon.com/Denon-AVR-1712-Surround-Receiver-Black/dp/B004ZP72MU
If this is for home theater, I would recommend something like Klipsch over Aperion.
Fro mains (left, right, center) I would get:
Left and Right:
http://www.sounddistributors.com/buynow.asp?action=detail&prid=661&crid=250&cat_name=Klipsch+Tower+Speakers $1200
Center:
http://www.sounddistributors.com/buynow.asp?action=detail&prid=671&crid=242&cat_name=Klipsch+Center+Speakers $1400
For surrounds (4 of these)
http://www.sounddistributors.com/buynow.asp?action=detail&prid=337&crid=248&cat_name=Klipsch+Surround+Speakers (4 of these at $249 each = $996)
For subwoofer:
http://www.hsuresearch.com/products/vtf-15h.html (Around $1100 shipped)
The total so far would be around $8800 for all the above including the Epson 5010 and a $1K screen. Depending on your screen, you could easily save some money there and also getting the BenQ would save you $500 (or around $8K total).
You also need to consider things like a projector mount, cables, and a universal remote. Budget another $500 or so for all those items.
This will still keep you below your $10K budget.
If you wanted to save some money on speakers but still have a very nice sounding home theater consider this deal:
http://www.hsuresearch.com/products/hybrid15pkg.html The hybrid 7.1 system would be around $2100 shipped for 7.0 speakers and the VTF-15H sub. With the Epson projector, screen, receiver, etc this speaker package would put you around $6200 shipped and would sound quite good.
