nomo,
5%. Wow. I've never heard of anyone mixing a natural tobacco extract at that lean a percentage. Not saying that you can't or shouldn't---your palate is the final judge.
The typical range of mix percentages I use with my extracts varies from 15-30%, depending on type (pipe tobacco blends seem inherently to make stronger extract, so they get mixed closer to 15%, while cigars don't extract with as much flavor, so I mix them richer, closer to the high end percentage) and the particular tobacco used to make the extract. I've never mixed an NET juice from any homemade or retail extract (my own, my home extractor buddies, or MyVapeJuice retail extracts) at less than 13%. So, 5% is a big difference.
Simple-soak PG/VG macerations tend to be very dark in color---sometimes almost opaque---although the liquids made from them are often/usually lighter.
Maybe it's a difference in sensitivity to flavors, or just a personal preference thing. Whatever it is, I'm surprised and impressed that you mixed your extract at 5%. Seems like you're very happy with the results, so I'll just say Cool! If it ain't broke, don't fix it. LOL.
Your last two questions about using PGA, and if so, how much, have no pat answers. It's up to you.