How to read a ductulator

I have a Harbor Freight 1HP 660CFM dust collector hooked up to a Rockler Dust Right. Then a 2.5in, 10ft flex hose coming off the Dust Right that I hook up to whatever tool I am using. I have long suspected that I am not getting 660CFM or anywhere close to that. So I bought this anemometer off Amazon. It is measuring 1608 FPM at the end of the hose. I've used formulas found online and they show I'm either getting 67CFM, 49CFM, or 6,893CFM.
The formula I used was CFM = (fpm*area), found on this website.
The anemometer does give readings in CFM but the reading was averaging 1705 X 10, which to me says the CFM is 17,050 and that can't be accurate. Can anyone help me out?

https://imgur.com/RgAdeA7
-1500 sq. ft. 1-story ranch (mid-1970s)
-13 year old American Standard 2.5ton 14 SEER (1000 CFM air handler)
Compressor on outdoor unit has gotten very loud and is no longer heating the home. Have gotten several quotes that I'm comfortable with for outdooAH replacement, however out of 4 different contractors one brought up concerns with the existing duct work.
All of the different contractors are in agreeance that the current system was probably installed by a "friend of friend" rather than an HVAC company. One of them mentioned that the main supply line was too small (he tried to claim they wrapped it in extra insulation to make it look larger than it really is) and in his quote offered to replace the first 8' on either side of the plenum to bump it up from 10" to 12". His claim was that the unit could have failed prematurely because of too small ducting causing higher pressures. Personally I feel this is an attempt at tacking on additional cost to his quote, since none of the other contractors even mentioned a problem with the duct work, other than the return being too small (saying this is common with R22 systems).
There has never been an issue with heating or cooling the house when the system was operating normally, but the two rooms on the right-end of the home do seem to be a few degrees cooler than the rest of the house, regardless of season (it's been suggested this is because that side of the house faces north). Only one of the contractors brought up and discussed a manual D/J, which he said he'd be more than happy to do, but based on the current setup it's not really necessary (important to note this is NOT the same guy who said the duct work was undersized).
I'm inclined to believe this is much-a-do about nothing. I never noticed howling vents or issues with pressure. I've read enough about current day heat pumps to lead me to think 13 years is not necessarily "bad" (and that I would have experienced trouble if my ducting was undersized far earlier than 13 years).
The same contractor who offered the manual D/J also gave me a quick run through with a ductulator and showed me how what I have should be sufficient, based on selecting a different friction rate. All quotes include a 2.5ton outdoor unit with a 1000 CFM air handler. I'm guessing that even the 10" runs on either side are sufficient because I have a 2-way duct setup with the AH in the center, rather than the AH on one end. Is it too simplistic to think that because my AH is right in the center I can presumably half the CFM going down each side of the trunk (I understand this isn't 100% accurate, since you may have different CFM requirements at different vents based on room size/run length, just looking at a ball-park). Thoughts? I kinda feel this is a case where one person put enough fear into me about this to be overthinking it.
Thanks.

I posted a few weeks back looking for some help with building proper ductwork. I went through 2 years of school to obtain associates degree in HVAC and then separate classes to obtain my HVAC Contractors license. Through both of these, there was barely any teaching on building ductwork. I worked for a few years for a rental company, where I was doing a mix of HVAC along with other skilled labor jobs. Now I'm out on my own and I've realized I have no idea how to build a ducting system (other than building a box plenum and spider webbing off of it).
So here is the layout for the house I'm working at.
Basement: http://i.imgur.com/fm2RkEi.png
Main floor: http://i.imgur.com/mi0OoJf.jpg
I'm installing this air handler. http://www.alpinehomeair.com/viewproduct.cfm?productID=453066016
I'll also be installing round metal ductwork.
On the main floor layout, there are red dots that represent ducts inside walls that have been covered up with drywall and I won't be changing out. These supply the second floor. I'll just be tying them into my main supply line that I'll be running.
I'll be setting the air handler in the basement where its labeled HVAC. I'm only running ductwork to the rooms on the main floor. These will be ran in the basement through the floor. Now this is sizing that I have figured out with my ductulator...

• Living room - 6 inch line
• Dining room - 8 inch line
• Kitchen - 8 inch line
• Bath - 4 inch line

This is where I need help. I read that with long supplies of round duct, I need to gradually decrease in size as the length grows away from the unit to keep static pressure consistent. I just have no idea to where even start with you what size to start with and at what intervals that I need to step down sizes. Can anyone help me or point me in the direction of where I can find information on this? Do my supply line numbers looks correct? Should I increase or decrease.
PS. For my return, since I can't open up any walls to install a return on the second floor, I plan on installing a large return at the bottom of the steps on the main floor or where its labeled Hall.