Yeah, I would say you don't need it. The gentoo guide was written with external USB plugin adapters in mind. These generally have an install image on them that loads first, thus the need to switch the mode.
> Also usb_modeswitch is in portage. This is not mentioned in the wiki.
> Might this part be outdated?
Most likely, the guide is talking about 3G adapters and was last updated in 2019 :)
>
> /etc/wvdial.conf
> [Dialer Defaults]
> Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
> Modem Type = Analog Modem
> ; Phone = <Target Phone Number>
> ISDN = 0
> ; Username = <Your Login Name>
> Init1 = ATZ
> ; Password = <Your Password>
> Modem = /dev/ttyUSB0
> Baud = 9600
>
> Does it matter it says "Analog Modem"?
>
No, that tells wvdial to expect a standard AT device. Despite it being digital there is still a legacy device interface to setup the connection.
> Does using wvdial result in no need to use minicom like mentioned in [2]?
>
Yes, like most things in classic UNIX/Linux there is more than one way to do something.
wvdial will run a chat script and set up the modem, make the call, and then hand off. Minicom is a terminal emulator and you would be connecting directly to the device and issuing commands. If the the wvdial script failed, you run the commands in minicom to test, for example.