Scott-S6

A few things. First, you don't need an application to export MFDs. Both Helios and Simapp cause more problems than they solve for MFD exporting, imo. Setup your viewport file properly and stop using them for that. Helios has nothing to do with the exported MFDs, EHSI or DED in the pic - all done simply by configuring the viewport file properly.
You can't export a piece of the cockpit like you're asking to do. What you can do is use an app like Helios to draw the gauges you want in the arrangement you want. It's not difficult at all. (the gauges aren't working in my pic because I no longer use them and have removed the helios interface, I still had the profile around though)
I would suggest considering if those gauges are actually useful to export. If they're strictly for eyecandy then fine but I have found that a large RWR is much more useful in the Viper and that's how I use the center screen in that aircraft.

If you mean - do RS offer a base that isn't force sensing? No.
ETA, they do offer a gimballed base for eurofighter as part of their professional range. Price on application...

You need to look at the available resolutions and calculate what the pixel density is for each - i.e. they must all have the same pixels per inch. Then it'll work the way that you want.
Remember that the game has no idea what the physical size of the monitors is.

That is the optimal way to do it, it will work fine.

Got it. I've been working on something to automate lua edits and it's incorrectly edited the EHSI_init.lua. Killed the instrument completely. Entirely my fault. I'm now wondering how long it's been dead without me noticing... Easy fix.