I can help. My sewing is my stress relief. My passion, my something I always have to do! I love sewing, and love talking sewing. If anyone has a sewing question, I'm happy to answer!!!! -nobia
About a 10/70 needle should work for jeans. You can also find thread specifically for jeans at places like JoAnn's.
Sgt Mom
Everything becomes a little clearer, I realize what life is all about. It's hangin' on when your heart has had enough, It's giving more when you feel like giving up. ~ In My Daughter's Eyes, Martina McBride
When you're hemming the jeans, are you planning on totally removing the current hem threads? If not, they'll be very bulky, and tough on any needle.
I usually use Singer needles 90/14 I believe is what they say.
Denim thread is great specially if you want them to look like they did when you bought them, but it's a pain to thread sometimes. Gutterman makes it in several color ways. Personally I just use regular thread that matches the seam thread.