No they are very playful they will always not be to old to be your friend!
Male guinea pigs can succesfully imprenate a female guinea pig at (I believe)only 8 weeks of age, however it takes about 9 months for the guinea pig to be fully grown.
The best age to breed your guinea-pigs is 5 months to a year old.
between 6 and 10 months for a female, not particularly important 4 male
guinea pigs are born with fur unless the are skinny guinea pigs ( breeds with no hair)
No, guinea pigs need a male around in order to mate. What probably happened is your guinea pig was pregnant when you bought it. This is quite common since guinea pigs are hard to sex when they are young but can however, reproduce at a very young age.
No. Male guinea pigs are sexually mature at around six months of age. o yes get closer
Male guinea pigs have been known to make a female pregnant when they are only a month old. But usually the male becomes fertile and wants to breed around 3-6 months of age. If you are planning on breeding, I suggest not to because the risk that the female will die giving birth or that she will give birth to "lethals" (babies without eyes or have crooked teeth) is high.
yes they can guinea pigs can be trained any age but if you train them its best to start young!! : )
About 4 weeks of age.
Male guinea pigs CAN harm newborns, as they aren't fully aware of the situation. i wouldn't recommend keeping newborns with the father. They should be feeding with the mother. After 4-5 weeks the males have to be separated from the mother as they become sexually active at that age, and can impregnate the mother.
guinea pigs are born full functional they are miniature versions of there parents with proportionally big heads
it is hard to age a guinea pig but if its over 1kg then its over 1 year old