Haha that's a lot of questions! But its totally understandable.
First off let me say welcome and congrats on the Nismo! Wish I had the extra cash for one when I bought my Z
As far as an audio shop in Orlando, I live in cocoa beach so I dont many of the shops out there, some of the others can probably weigh in on that. I have a lot of experience doing that stuff so I just do it all myself anyway. Thats another option if you're interested, you can come to my place and I'll install just about anything you need for less money than a shop would usually charge.
I'll post a pic of my zenclosure, I love it. You have the option for either 10" or 12" sub's, one firing out towards the back hatch or two firing up towards the roof and the people. I have one Alpine type R 12" sub with a 400w kicker amp (soon to be an alpine v9 amp) and it hits pretty damn hard. We don't have much air space in cabin to move so you dont need a crap load of power.
I mounted my amp under the hatch floor thing, on the metal frame behind the seats. That amp runs cool so there's no airflow problems. Plus its hidden and looks clean as you'll see in the pic.
The Berk hfc's are good, but I'll sing the Fast Intentions praises till the day I die. Not only do they make an OUTSTANDING product, but they have customer service second to none. IMHO they are the best company on this forum as far as CS and dedication to product quality. Plus it just sounds dāmned sexy.
SO. SEXY.
As for shops to install it, again we could do that here at my house if you wanna learn how to do it and/or save some money. Otherwise PRS is a great place to go, while others might recommend Marti at Rev Works.
Last but not least, dont forget to check out our FB page and group, linky's at the top post. We're pretty active there and can answer just about any question you might have. Also, try to come out to one of our meets sometime and introduce yourself, we can actually be kinda fun sometimes
Welcome to the forums!
Zdayz 2014!!