hey there.
for peeing and pooping messes i don't think you can really change their bathroom behavior, only wipe paws and butt at the end each time. that's what we have to do. she walks through her pee too and she sometimes gets poop stuck to her butt. we use wipes to get it out, but you should also either take the pup to the groomer and have them trim her anal area and also they can shave the ears with trimmers, or you can buy some trimmers (i think beard trimmers for men work!????) and you can just shave off the very tips of the ears and also you can then see where her ears/hair is and take scissors (rounded top ones) and trim the hair into a V on the tip of the ears. also for trimming backside, you just hold the tail erect in one hand and use the scissors and trimmer to trim up the buttox area and in between the legs, also you can scissor the privates if needed so pee doesn't get the hairs all wet.
for the question about age see this chart:
Yorkshire Terrier - Yorkie Puppy Growth/Weight Chart - watch us grow
it appears she will be over the 7 lbs standard, so tea pot indeed
i would guess about 8 lbs or so..but u never know, Sadie is 2 lbs. 5 ounces now at 20 weeks old, some say she'll grow to 10 lbs when they saw her at 3 months they say to take weight, double it and add one pound. so should should have been about 5 lbs...but i don't think she will be. i'm thinking now she'll be about 3.5 max!!
hope this helps and congrats your girl is beautiful!!