Weight gain is a slow process so 1 to 2 weeks will net you no measurable results.

If she is a" real" long time friend I think she would understand.
If not then she isn't really a friend that will accept you for being you.
I lost a few friends over my weight mostly guy friends tho'.
I have some women friends that constantly talk about being fat and it always feels weird because I am the fat one and they are not fat at all.
I would send the email and just be done with it.
You said your piece and she knows how you feel. Keeping things all bottled up and stressing over it is just not worth it.

Too many variables to suggest a defined number.

Question 1.
Its really hard to say gaining 25 lbs may be harder than you think but in my case I noticed the first 10 lbs I gained.Others if they did notice never said anything.
I could always tell when I put on weight by my underarms getting thicker and fat on my thighs getting thicker and rubbing.
Question 2.
Being bloated by eating more than what you are used to is normal.
Question 3.
Eat whatever you want just larger amounts.
Question 4.
Lets say you do gain 25 lbs yes you will probably have to go to a larger size in pants and shirts.
Question 5.
Eat whatever you want just more of it.
The is no real magic food to make you gain weight.
Ice cream and heavy cream have lots of calories so having some before bed time is a way to get your gaining started.
Eating calories then going to bed and not exerting any energy will help you gain.

I had someone ask me if I had any dealing with catfishing on here and I had to look up the term.
I honestly had no idea what the term meant.

Thats always been such a sexy romantic thing/fantasy for me.I would love to do that again but fatten up a slender girl to my size.

Avacados are very soft and very fattening

I think being ignored in chat is pretty common.
I know I have gone in there and had no one respond.
The main thing is don't take it too personal because you can't force people to chat with you.

Cute story.