Probably not. Have not tried it with NylonX but all other nylons I worked with have no problem with it. If you go past the glass transition temp on any material for extended time some annealing might be going on. This most likely wont be a bad thing. It will get a bit stiffer. Annealing - depending on the Nylon will start at about 90 C. You can go as high as 140 with Nylon 6 or 12 as the melt point is at about 170-180. If you exceed 90 C its important that you leave it in the printer until the bed and part cools to room temp. Especially if you have an enclosure. If you "rip" the part of the build plate at lets say 110 and put it in the cool room it most likely will cool unevenly and warp a bit.
Your problem is that most likely the Nozzle is not tight. Check the proper installation instructions for your hotend. It could also be the the threads got stripped. If you have a hotend where the PTFE tube goes all the way to the nozzle, take the PTFE tube out. Check the end make sure there is no damage and its cut straight. Then turn out he nozzle 2 turns, insert the PTFE tube all the way then tighten the nozzle to the specifications of the hotend. If its all metal check the assembly instructions. Nozzles will get loose after some printing and then you get leaks
I have tried "heatweld" 910 the dremel method failed but using a solder iron and a piece of filament like solder kinda works even though in my case it did not look that hot but it did a decent job mechanically. So I assume it will work at CF nylon too. I needed to turn the iron up to 350 minimum though
A big brim might help. and you can squish Nylon almost like petg so up the thickness of the first layer to 80% nozzle diameter and lower the Z- offset as much as possible while still getting a nice first layer and maybe try some gluestick. even on garolite which I asume you have it helps and up the temp to about 90-95 and definitely NO FAN. Nylon does not like a fan and put a box or plastic sheet over it to keep it warm inside and drafts out that cuts down on warping too. just try to somehow exclude the electronics box
If you write to gcode file then its saved in there as comments. To my knowledge MC does not have a feature like SLIC3R to load settings from a gcode file. You can save different profiles like "MH Build PLA 04nozzle no support" and then start off with that and change the support settings for example and save it as ".... with support" etc
I think you might run into problems with PETG as the temp is pretty close on the border where it makes sense. To have It snap and not break I would use either HIPS or a Nylon. Probably Bridge or alloy 910 if you need something harder. IDK if your printer can print HIPS and Nylon. But that would be my first choice. HIPS does not go soft up to about 100C and Nylon even higher
That is a great question.
I would say try to open it up in MatterControl 2.0 which can be downloaded from mattercontrol.com.
MC 1.5 is extremely outdated and likely had a bug in the software which impeeded opening larger files.