Amplifier or splitter with amplifier, internet speed, XFI speeds

Hello everyone, my name is Karl.

This is my first post, I need some help, advice, some clarity (obviously why I'm here haha). I am somewhat tech savy and I am mechanically inclined. But the coax dB and frequencies and interference and such is all new terms to me since I have never ventured into this type of stuff besides connecting equuipment or putting a splitter in to have a cable ran to a new location. I have the X1 package, 1 gig internet ect. I did double check my speed was 1gig on my account. I have the newest white XFI modem( wish it wasnt white). Was having some DVR cable box and internet issues, like dropped signals, blotchy speeds, cable box freezing up and such. When it was first added to my account a couple years ago, the tech did not go under the house to install the amplifier that usually the X1 platform get when signing up but he did say my signal from the pole to my house was 0bB, which I was told the ideal number. So I went under the house noticed a BUNCH of splitters. Probably outdated, some a lot older and some newer. Not sure, who cares. Got get rid of all them. I went out and bought a Antronix VRA900B cable amplifier "9 Port Bi-Directional Cable TV Splitter Signal Booster/Amplifier with Active Return Zero Signal Loss VoIP Telephone Bypass Port." Ran the cable from my outside directly inside through the brick, no splits, into the "in" of the cable amplifier. I ran the "power" from the wall outlet adapter to the the 15V 400mA port. Next I ran the coax cables (all pre-existing installed with home some thicker some not so thick) from the "output" ports to all my tvs boxes. My cable modem coax cable is newer (thicker coax), it is run directly from the amplifier to the coax wall outlet (like a electrical outlet but coax and attach the cable onto) which then a short 3' included comcast cable connects it to the modem.  My ultimate goal here is to have a very good TV signal to all my cable boxes and have the best cable modem performance WiFi distance/speed/strength/reliability that is possible.

My questions are the following:

First things first, is this amplifier ideal for the XFI platform or should I swap it out to another one or a better option?

Do I have to connect my XFI modem to the "-4dB VolP output" (not worried about power outages due to having a generator) or would it be better/ stronger to one of the regular "output"? Looking for the better signal strength output.

Before, after, swapping cable outputs/inputs, do I unplug the amplifier from the wall outlet?

Do the amplifiers ever need to be powered down to reset and how would you know if they do and how long to keep powered down to reset?

The unused "output" ports, do they HAVE to have terminators? Does the speeds and operation of the amplifier differ greatly if not?

The position of my modem is directly in the center of my home, about 5' off the floor on a desk. May sound dumb to ask but, does a cordless phone that is connected to the modem that is 3' away on the other side of the desk effect the WiFi? They only gave me a 3' phone cable to attach to modem for landline, but I dont use it regardless. Should I just remove it?  Also there is a small 2 speaker system, on the desk with a subwoofer on the floor. Would that have any effect on the Wifi also?

Your guys help is GREATLY APPRECIATED!! Thank you all in advance! Hope everyone is having a good holiday weekend.