Best Print on Demand service for T-Shirts ?

I have a niche Instagram account and will start fb page too with same name.
I want to start my own website for selling T-Shirts and other print on demand products, So i was thinking to use woo+wordpress.

1.

Please suggest me good print on demand service.
I researched and fount Printful to fulfill my requirements. But their base price is too high.

For example,
T-shirt International = 12.95(base price)+10(int shipping) = 22.95
T-Shirt US = 12.95+5= 17.95
If i include only 5 bucks per shirt, will anyone pay 28 bucks for it ?

since most of my followers are from worldwide should i use printful?

2.
I already have 50k followers in my Instagram account, and i want to start fb page too with same name. What is best way to gain initial followers/like on my fb page ? If i use fb ads for initial boots, how to get cheap followers/like (real from fb ads)

3.
If i use wordpress for my pod website, what is best theme fir it ? ( Most of my traffic will be from Mobile )

4.
I too want to use fb ads, It would be great if you could suggest me to start a good fb ads (i am new to fb ads)

1-
The best option in your case is Teechip Pro when you can create a store with your products using your own domain name.
2-
Growing an fb page is pointless in my opinion since the reach is too low , better grow another IG account in diffrenet niche posting shoutouts in your first one.
3-
As i mentioned above Teechip Pro will save you time and money and it's a way better option since you don(t have to deal whith the payment gateway and other technical stuff.
4-
There are a lot of fb ads tutorials on youtube you can learn pretty much everything .