I've never had girls but I would love to have some eventually!
Here's the take on my boys
Personality
They are so cuddly, and they don't mind if I have one out for a time and then switch.
Friendliness /bonding with each other and you
Boys are harder to bond and you can usualy only have them in a pair, so adding more over time is out of the question. Both of my boys are equally bonded to me, they will snuggle on my neck and give me kisses constantly
Taming
I'm not sure, I just kinda get them out whenever and they deal with it. Although, after I got my second boar he got used to me much quicker then my first and I think it's because he had a little piggy support from the first and told him I was okay
Health issues
Boars can become impacted and you have to clean out their boy parts quite often to get any hay/bedding out of there and it's really gross.
Anything else you can think of
Boys tend to mark and they can smell more. Also their grease glad can be quite yucky at times.
If I were just barely getting my piggies I would get a neutered boar from a rescue and then add my girls so that I could have as many as I possibly wanted and they could live as close to the way the wild Guinea pigs do.
You can always have as many girls as you want but the boys are limited to two GOOD LUCK!