Ball Python Food Question

So I asked out here for a place to order rats for my bp. I used one of the suggestions. They are small rats. The place stated they do not put them to sleep and package until you order and I do believe it because I got them 3 days later and thawed one immediately to feed my girl and a flea came to life in the bag (no lie). I killed the flea and then fed my girl.

So here are my questions:
- Should I worry about frozen fleas or flea eggs? I know in wild yes she would eat them but she is in my home and I want to prevent parasites as much as possible. I will not put a live flea in there for sure!
- The last rat (last night) had a yellow coating on his fur..may be just urine but have you seen this?
- She is about 5 inches at her fatest point - are small rats the right size for her or are they too big? She is about 2 pounds and 43 inches long. Just want to make sure she is getting right size.
- Is there such thing as overfeeding her? She seems to tell me when she if full by going in her hut...but is there a limit like 2 a week or something? She is almost 3 years or right at 3 years old and did not eat all winter for 8 months.

I can only answer if it were me and my snakes: I would not feed infested rodents to my snakes. Just me.
I'd think that if your snake is 2 pounds (=a bit over 900g) then feeding a 90-100g rat every 7 days should be fine.
I *think* that the yellow is the keratin in their hair. I am not certain as this info comes from my high school son who is of the impression that he knows all that I don't (...may I live through this stage!!)

I wouldn't feed, because if they have fleas....what else could there be??? As in internal parisites....not good

Good point you guys...my only issue is that I have ordered them an now have a bunch so would like to find out for sure if I need to be concerned.

It did freak me out to see a flea alive in the bag....I mean it was frozen....I thought that was WILD.

So does anyone know...I ordered these from The Big Cheese which was suggested out here. Wish I could find my old thread but cannot.

Ugh. I have always ordered from The Mouse Factory and I tried Big Cheese a couple of months ago and they rate a very distant second.
The Mouse Factory is SO MUCH better :D