pups, weaning,re-intro of male

Question
1)If the pups are all male, will they eventually fight and bite each other's ears?  I see in a neighborhood pet store that they have many males together and while I was at the store, I observed very aggressive biting/chasing behavior with the males.  I felt sorry for one very cute male, who has lost almost the entire floppy part of one ear and has slits in the other ear. So I brought him home. He is a very sweet male and seems to not mind the new gp pups at all in the x-pen and even allows my 9wk old dwarf male rabbit to 'cuddle' into his body/neck.   
2) Do you think if I keep 1 male pup and put him with my older sweet male, they will get along for the long haul?  Especially since I have to keep the male(s) from the female (to allow her to recover).
3) Do I need to be very careful and not allow mother/son and father/daughter to mate?
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Followup To
Question -
I have a gp who had babies on St. Patrick's Day. I believe we have 3 males. They are almost 3 weeks old and I have seen each one of them trying to mount thier mother (I took them to neighborhood pet store, where I bought the mother, and they confirmed the males).  
I have read on the internet that pups are usually weaned at 3 weeks.  At what time should I separate the pups from their mother?  They seem to be eating fine (pellets, timothy hay, fruits and veggies).  In addition, how soon can I introduce a male?  How long does she need to recover?
Answer -
Hello cherri

The pups are weaned at four weeks of age. You should not put the male back in for at lest another three months otherwise the mother will tire and she will not live as long as she should. The pups can be kept together for the rest of there lives if you are planing on keeping them.  

Answer
Hello again cherri

The guinea-pigs in the pet store were either introduced incorectly or there was a female in with them that would make them fight.Dwarf rabbits and other rabbits shouldnt be allowed near the guinea pigs because have you ever seen a rabbit stomp its hind legs? well when they do it makes a loud noise whitch will scare the pigs also if the rabbt stomps its feet and the guinea pig is under foot then the guinea pig is going to either be in critical condtion or dead, also when the rabbit is adult it will mount the guinea pig and if its a female it will treat it very badly not letting it go where it wants unless of coarse your rabbit is spayed/neutered. You got a new guinea pig form a pet store and put them stright in with your old pigs? What if the new pig has an illness that you cant see? what if the new pig has lice? any new adtions should be kept in a different cage in a different room for at lest a week you would also need to wash your hands before handling the new pig adn change any clothig that the new pig has touched to pervent the others from getting ill. Two or more males can get along great, brothers get along very well and if any more pigs are to join the brothers then they should all be the same age, or with younger males an older male should work too. Just be sure that once you have the male pups and the male you bought are together that they cant be taken out for breeding for a few months adn then put back because after a male guinea pig has been around females they can not be kept with males again. You do want to be sure that they dont inbreed (the breeding of related pigs) because it causes all sorts of problems including missing eyes & extra toes at birth, internal deformaties and shortened life span.