Ultimate Grass vs. HDR Skies packages--huge black areas.


I just composed a message then struggled for 20 minutes to “attach” this preliminary render, with theblenderguru’s “Ultimate Skies” add-on, plus his collection of HDR skymaps (to provide light into the scene “as if” you are outside on a sunny/cloudy day… Don’t know what happened to THAT message! Oh well… ;o)

So, while doing this, I find that the “F3” key to save a version of the current render-image, DOESN"T work! It’s greyed out on the file menu… Had to use a Win.10 “external” app to “snip” a screen-shot to illustrate the situation…
two types of “grass” and one type of weed (yellow dandilions) each set a 50,000. instances, with no “children”…
this image took about 8 minutes to render 4 or 5 “progressive view” passes…and during the construction of the scene, I couldn’t get the Ultimate Skies add-on to show me the various different sky environments there were to choose from—except one at a time, in the right-hand toolbar area, in world-textures/images… NOT the full-screen “easy to pick from” menu-screen demo’d in the salespitch on Andrew’s website! I purchased both these items as soon as available, but health and technical issues (and shortage of $$$ to FIX those technical issues) have slowed me down by nearly a year and a half!
So I’m starting over from SCRATCH with a fresh install of Blender 2.7.6, and two days of skull-sweat to get the “skies” and the “grass” add-ons installed to this point…

SO, WHAT am I doing wrong (if anything) with the installation, and WHY don’t the “skies” preview tabs not show up within Blender? AND come I cannot SAVE anything… (F3 key not working?) AND (finally) why am I getting huge black areas surrounding my scene? How to fill them in, compensate for them? and why is my system feeling very sluggish and cramped–even though I have a “Titan Black” GPU with 6.GB of RAM onboard (hot stuff when I purchased it to go into the new “box”, about two years ago…an “eon” in computer-gear time, I guess! ;oPP

The usual T.I.A. for any tips/tricks, or advice on these problems (& sorry to shoehorn all of this into one message!)

HDRs (or any background for that matter) will only show in perspective view, not orthogonal. Looks like it is perspective, so it should show it properly.
Does it do the same on an empty file. Maybe supply the blend and we can see better (or maybe a screenshot of the whole screen with the World tab open).
I must admit, I have never had this problem so it is difficult to relate.