A few half marathon questions

Hello! So I have a few questions ahead of my first official half marathon in 13 days ish. I run about 22-30 miles a week, and I ran my first half yesterday afternoon (just in my neighborhood) just to test the waters. At mile 12.5 my stomach started dying (really sensitive stomach over here), and I also had a bottle of water with me. The first two hours after finishing, I legitimately felt like I had the flu. Didn’t really do any “extra” fueling that most runners talk about (carbo-loading, etc.) and I feel fine today with the exception of just being a little tight. I also feel fueled back up today nutrition/water wise. So some questions so I do it right this time:

  1. Do I need to do a GU or energy past mile 8? (I’ve done up to 8 miles before and felt fine after my run…)

  2. What is the best thing to eat the night before and right after the race? I plan on having a banana the morning of the race (again, have super sensitive stomach).

  3. This is so silly, but I have the WORST blister on the top of my toenail and almost feel like my toenail is bruised? Does this happen to anyone else / how to fix so I can start running again?

  4. Leading up to my half, I did 23 miles this week. And my last “long run” was 8 miles three days before and a 4 mile the day before. What’s recommended for race week?

Appreciate any other tips/tricks/do’s and don’t’s!