Welcome to the forum. I have a BT 5245 and am a newbie as well.
I agree with everything Leisure Time Larry posted and here is a couple more thoughts.
Searching this site and reading the Class B+ sub forum has been very helpful.
As well as YouTube and other websites.
Have you found this link for RV manual, vendors, and component manuals?
(at the very least having a pdf version on my tablet while on the road has been helpful)
Unfortunately, since you bought the rig used it might be that components and appliances have been swapped out and/or heavily modified by previous owners and your vehicle maybe much different from what rolled out of the factory.
You should be able to look up the vendors of the individual appliances and download manuals from the net.
There are a few off brand components, like the aftermarket dash radio that was installed in my rig that was real difficult to track down. (I uploaded a scan of it on this web site, search "Control of Rear Camera?")
I only sent one email in to Gulf Stream and did get a reply so hopefully you will to. But I have had good luck going to a local distributor of Gulf Stream RVs and getting service and help from them.
My propane furnace and water heater has electric start but my cook top needs either a match or a pizo-electric flick to manually light that. The oven we haven't used yet so not sure.
I hope you enjoy the adventure. As for me, traveling around in today's world using my own bathroom and bed is alot more assuring than sleeping in a strange motel!