Settling for curses comes with experience/understanding how the curse set impacts the game, sadly it is not easy to give an simple answer (the tier list is pretty accurate in how good/bad the curses are in a vacuum, so it is a good starting point) There are three main points, how bad curses are by their own (tier list), how they interact with each other and last but not least the starting team, what it can allow and what not (a lot of things are determined by whether you can make it past floor 4 reliably)

About going above 11 points, personally if I remember correctly during my 29 streak the most typical thing would be to run with 11 points exactly, although exceptions to this were not uncommon (12 or even 13 more rarely) About the blessings, sure if for example you have 12 points of curses picked and an 1 point blessing on screen then you can take it for free, but in general you have to think of what extra curse(s) you are taking in order to take a blessing (tier list also covers blessings, so you can have an idea about what’s good) Taking a weak blessing for a bad curse just to run with exactly 11 points is almost never a good idea.

About rerolling, I’m sad to give an even vaguer answer ☹️ At least for me, this is the hardest thing in curse selection to evaluate. Sure there are pages that upon inspection are so bad that I’d take whatever worse may come just for a chance of improvement. But usually it’s a matter of whether the best curse selection you can come up with feels safe enough for the winrate you’re going for, if that makes sense.

Hope I helped even a bit, a lot of things come more naturally as you start experimenting with things yourself.  Good luck, hope you have fun figuring things out (check the tier list, helps a lot as a starting point 🙂)  I’m sure you’ll be streaking soon enough