This topic seems to surface frequently not only here but on other Forums. Many explanations/descriptions are given, some of them very good, but there seems to still be a lot of confusion as to what will work and how to do it, so maybe this will help.
First, everything after your regulator including the black pipe manifold and the Tees going off of it to your appliances and furnace is low pressure. No exceptions that I'm aware of unless you have added your owns stuf at the tanks.
Second, most grills come with their own regulator and will not work on the LP side of your propane system as is . You can't regulate the pressure twice. Again, no exceptions that I'm aware of.
Every gas grill I have ever seen(there may be some others out there) is assembled so that you can remove the regulator and and equip it with Quick Connect fittings. I'm not sure that all LP QC fittings are compatible with each other. My Outback outdoor gas connection is made by Fairview, Most likely, Keystone uses those exclusively, but I won't guarrantee that. if there is not a tag on your QC, you can probably call KS and they can tell you whose product they used. Fairview gas fittings are available all over the Internet. Google is your friend. For RV LP gas QCs, you will most likely only run across 1/4" and 3/8" fittings. My Outback used 1/4" and I'm betting that is probably a standard with KS. BTW, you can't use HD or Lowe's fittings made for air compressors.
This photo shows a male QC fitting attached to a Weber Baby Q. The thread size, if I remember correctly was 1/8" NPT. The QC fitting is 1/4" so you are going to have to possibly use a couple of brass fittings to adapt it to the grill control. It may seem like you are gong to end up with a Rube Goldberg looking setup, but it's not that bad. Also, it seems that if you put the male part on the grill and the female component on the hose, it just seems a little easier to handle. That has the hose made with a male nd a female part, so in the unlikly event you need and extension to reach somewhere, you simply make up a duplicate hose.
This photo shows my LP hose with a male QC(trailer end) and female coupler(Grill end). The advamtage of making the hose in this configuration is that you can use the trailer's QC for either the outdoor kitchen stove or your gas grill with no need for any other adapers or fittings.
A word about pre-fab hoses. They will usually come with male or female NPT threads or swival-flare connectors. Either type can be adapted to the quick connects you are using. If you are not sure how to go about it, take your hose and QC components to Home Depot. Lowe's, or a Propane facility and tell them what you want to do. They will have what you need. If you DIY, be sure to use YELLOW thread tape on the NPT connections or Rector-Seal #5, not the white teflon plumbing tape. Flare connections do not get taped or doped.
I was laying on the ground to take this and I was pretty close, so my depth of field wasn't great, but it simply shows how I used a 1/2" pipe nipple and a coupler to extend my trailer QC out so I don't have to crawl under the trailer to get to it
I hope this clears up some of the confusion about doing this mod. In fact, maybe the Moderators will like this enough to make it a stickie.