Here is my biggest advice.....lay it out on a table, and then frog it back to a good point, and when you get to the end of that row go verrrrrrrrrrrrrry slowly or else you will go into the next row inadvertently. Then, very carefully insert your needle.....if you do by mistake go into the next row, just put that one stitch on the other needle and knit it over.
Re the twisted stitches - you will know - they won't feel right, and those are easy to untwist as you knit.
A good tip for a new knitter is to insert a lifeline every 10-15 inches - to do that, you just thread a needle with some scrap yarn and run it along your needle through all the stitches. Then if you have to rip it, it will stop at the lifeline.....and then its easy to insert your needle and not rip into the next row.
Re that last stitch, maybe its just elongated looking because its kind of stretched right now. Your re-knitting idea is the right way to go...if it doesnt look right you can always go back another row or two