I have a similar monitor made by EIZO / Nanao. The purpose of the big chunky TTL/ANA switch is obvious: It bypasses the digital-to-analog conversion circuit in the monitor, and switches the 9-pin pinout from the TTL (CGA/EGA) specification to the PGA-like specification, most likely with pin 5 as "vsync" instead of "mode" (as used by the original PGA). This is a very common 9-pin analog pinout. Most of the time, these monitors also accept composite sync on the hsync input, making it compatible with the original PGA as well.
When in analog mode, all the other switches are ignored. In digital mode, the switches configure how the TTL information is converted to analog. The text ON/OFF switch seems to choose between a monochrome mode and a color mode. If you choose the monochrome mode, the two color DIP switches select one of four colors to display the monochrome text: Red, Green, Blue and Amber. When not in text mode, the monitor uses the CGA compatible pins for R,G,B. In 8-color mode, that's all pins used. In 16-color mode, the CGA intensity pin is used as well, and in 64-color mode, the CGA intensity pin is treated as second bit for the green intensity, and two further pins are enabled to be considered as second bit for red and blue. The Auto/Manual switch is most like for compatibilty with a pecularity of the IBM 5154 EGA monitor: It uses 16-color mode if there are 200 scan lines (compatible to the 5153 CGA monitor), while it uses 64-color mode if there are 350 scan lines. "Auto" selects automatic selection between CGA-type and EGA-type colors (usually the color mode switches don't matter in "auto" mode), whereas manual activates a fixed color mode set by the switches.
There are in fact two different 16-color modes. They straightforward one would have color 6 as "dark yellow", which is a quite ugly color. This mode is sometimes called the "AT&T color mode" (not related to the Olivetti/AT&T 400-line CGA mode), whereas IBM decided to display color 6 as brown ("dark orange"). My monitor does not offer two settings for "64 colors", but "16 IBM" and "16 AT&T". It is possible that your monitor uses the "16 AT&T" mode if set to manual 16, but uses "16 IBM" in auto mode with 200 scan lines.
I am not certain what the "h-width" (horizontal width) switch is supposed to do. Possibly it enables/disables a width adjustment control.
A monochrome video card like the MDA (or the EGA in "monochrome monitor" configuration) outputs the primary video signal on a pin not used in 8-color and 16-color mode (it seems IBM intended to have the a "universal" plug that can be connected to a color or a monochrome monitor, with a dedicated monochrome signal). In 64-color mode, that pin is used for "slightly more blue". My EIZO monitor does not support using that pin as primary monochrome input pin, so I had to make an adapter cable that re-routes the monochrome video pin to the "green" input pin. Possibly your monitor supports input as monochrome video in "text" mode.
I consider a monitor like this a very useful tool to have, because it will basically display anything you can not display on a modern TFT display, maybe including 1024x768 @ 87Hz per interlaced field (XGA). The model number 1435 suggests that this is a 14 inch monitor supporting up to 35 kHz. This would include 800x600 at 56Hz and the XGA mode.