I've had a few times where it all seems a little too much. Mainly when things go wrong or you just don't seem to be making any forward progress. I'm getting closer to the end of my build but still wonder sometimes if i will be able to finish it.
Sometimes a break helps, sometimes just talking it over with someone can put it in perspective (here or elsewhere). I'd avoid talking to non builders about it though as most will think you are mad and attempting the impossible so won't always give helpful advice.
If you get to the point of giving up/selling etc, I would suggest having a break for a couple of weeks before doing anything as it normally passes after a while.
As for the rivets I had some issues with them expanding in the middle of two parts and used a similar method as mentioned above (with the tubing) but using tap washers (all I had at the time).
The main things when squeezing is to keep the parts together and the squeezer flush, and not to over squeeze/use too long a rivet as it can cause the parts to bow away from each other (especially on bearing brackets).
Below is a picture of my 'tap washer' being used, This time I have the squeezer in a vice rather than the parts (I often find it is easier that way round, especially for nutplates and dimpling). The tubing will be easier to squeeze and it will also stay on and hold the rivet in place, the washer has a tendency to drop on the floor just when you have everything setup, and you can bet when you are bending down to pick them up the rivet drops out as you nudge it with your arm, oh and you will hit your head on something when standing back upright, but that is the fun of building :P
As for space I find it slows the build down a lot and can be very frustrating but has the added bonus that not only are you building an aircraft yourself (something everyone should be proud of) you are also doing it in harder conditions than most so it adds to the achievement as well as the frustration.
If you can get an hour with an existing builder/inspector you will learn more in that time than weeks of going through it on your own, I would highly recommend it if you get the opportunity.
I was lucky enough to do a LAA 'working with aluminium' one day course here in the uk (run by other builders) and I believe that saved me 50-100 hours of building time at least (as you get tips that will cut down on the reworking time).
That said I have lost count of the number of rivets I have had to drill out, normally when tired or rushing but luckily I have managed to avoid too many replacement parts so far.
You will screw up some more stuff before it is over, but you will learn the skills to fix it on here or elsewhere which will pay off even after you have finished.
Everyone goes though up and downs during building. Remember you are building an aircraft which is a big undertaking.
But it's like the old question 'how do you eat an elephant'.
...
'One mouthful at a time'.