Stacked up questions about UVs in Blender

Hi! 

First off: thank you for a really good course in UV mapping! I´m new to Blender since two weeks and really glad I found you at the beginning! :)

This exercise arouse a bunch of questions, and I posted them in my submission. But I have begun to understand that submissions are not necessarily looked at and graded by the instructors, but can be voted to pass by other community members (am I right on this?). At least happened for me today. It is therefore I now ask my questions to you here as well - sorry for the "spamming"/"cluttering". 

Here goes: 

1. I found two settings for automapping, both in 3D view and in the UV editor. Is there a difference? They don´t seem to be linked (checking one does not check the other)

2. I had problems moving/snapping some of the vertices in the UV editor when overlapping pieces for sharing UV space. This was the case for some vertices along the edge (actually the same vertex but represented on both overlapping "islands"). Is there a way to "align/move selected vertices to same spot in x/y"? When selecting one of the vertices both get selected. I gave up on that, so my UV layout for the sharp edge of the ax isn´t perfect..

3. I tried to get my UV´s as dark blue as I was able (respect to stretch, not angle), but even when UV´s went dark blue in the UV editor, I found some obvious UV stretching i 3D view. Shouldn´t it be rather stretch free if UV´s shows blue? Puzzled :/

4. I was warned; I wrestled with Cycles materials/texture node. Got really frustrated when textures didn´t show up at times. Created x amount of new materials etc. Is there a way to delete and clean up the scene from unused nodes (apart from reopening the scene (which didn´t clean out everything for me)? 

5. I sometimes had a hard time viewing the currently selected objects material in node editor. Is there a way of forcing node editor to "Show material on selected"?

6. It feels like I ended up with a smeared texture.. I found it hard to keep it crisp: either it went awfully jagged OR really blurry. At the end of my texture painting I decided to add a motif on the ax blade by sending it to Krita for external edit. It worked fine, but I believe my texture lost some sharpness in the process, and I later noticed some texture glitches along UV borders which wasn't there before. Does the texture get altered a lot after getting the edit back from external apps? Are there any tricks for having a 512 texture sharp? :) (I guess that separates Master from amateur..)  

Well, thats it! This exercise forced me to UV unwrap and forced me to tackle problems I would have abandoned otherwise, and it was fun!  

I guess some (if not all) of my questions get answered in other tutorials. Perhaps I should have taken the Shading course beforehand? Would really appreciate some pointers in that case!   

Thank you in advance! :)

Da Wide