Exhaust choices for new roof - details included

First apologies for the long post, I do want to include as much relative info as possible. My house is getting a new roof put on (GAF) and I am concerned with limited exhaust when choosing a ridge vent (GAF Cobra Snow Country with 18 SqInches of NFA per linear Foot). I did the calculations and thought about having Cobra Hip vents installed. The roofer said it may not look good (?) and then suggested two fans and a ridge vent over the garage (I know, no power fans with ridge vents). I called GAF to ask about their relatively new (Spring 2015) Cobra Hip Vent (9" of NFA per Linear Ft.). The lady I spoke with was not familiar with my type of roof construction (Hip roof without a continuous hip rafter) and told me that since their installing video showed a continuous hip rafter, then that is what I would need in order to have the hip venting. The lady also told me that I should have more exhaust venting than intake, I knew she was misinformed.

So I am trying to determine if I can get away with just ridge venting, or if I will also need hip venting or if I should just get two fans (which I really do not want).

My House with 8/12 pitch roof:
Drawing shows bird's eye view of the house, the colors are as follow:
Tan area is the heated area below the attic insulation.
Grey is unheated and non-insulated area (garage & porch).
Yellow is the false roof over the front entry door (closed off to main roof).
Green line at rear of garage is where main roof sheathing comes down to just about 2 feet above the attic floor (so a tight fit to crawl to above the garage)
Light blue is the soffit area (24 inches deep on rear, 12" on sides).
Red lines are the ridges, hips, and valleys.
Dark red circle is the current power fan (will be removed with ridge vents).
In the picture of the front of the house there currently is a gable vent over the garage, and a gable vent on the false roof over the entry door. The one over the garage will be blocked off, the one over the false roof will stay for venting.

Attic area to garage considerations:
The main roof sheathing comes down to just 2' off the attic floor, which looks to me like there would be an air pocket at the garage ridge. I don't think air coming in from the garage soffits would travel low to the main ridge vent, nor air from the rear soffits travel low to get under the sheathing to climb up to the garage roof ridge. So to me these may possibly be separate venting area (?):vs_worry:
With the above, I've separated the areas

Main attic area 32'x68' = 2176 SQFt
Garage attic 12'x21.5'= 258 SQFt

My current soffit intake:
Sq feet of soffits venting directly into the attic is: 218'
Soffit area into the garage is: 24'

Member Bud9051 kindly provided a number of 4.6 Sq Inch of vent per SqFt of my type of soffit vents.

218' x 4.6"= 1002.8"
24' x 4.6" = 110.4"

Using 300 rule:
2176 Sq Ft attic area' / 300 = 7.25' X 144 = 1044 Sq Inches of NFA needed. A 50/50 would be 522 intake and 522 exhaust and I have 1000 coming in.

Garage Sq Ft area 258 / 300 = .86' x 144 = 123.84" NFA required, mine is 110.4"


The ridge on my main roof is 34' long. With the ridge vent, about 6" on each end is not cut open, so about 33' then available. As above, GAF Cobra Ridge vent Snow Country provides 18" NFA per linear FT, so 33' x 18" = 594" of exhaust venting.

594" + 1002.8" = 1596.8 total NFA. Split 62.8% Intake and 37.2% Exhaust

To give a 50/50 for over the garage, I measured that 5.5' of ridge venting would provide 99" near a 50/50 without going over the rule of not having more exhaust than intake.

Other considerations: I live in Maryland, Eastern Shore, I get a nice breeze and some strong winds along the rear of the house with a relatively moderate seasonal climate.

Your thoughts?

Again apologies for the long post.
Thank You