Shaving under armpits, is encouraged in Islam mainly for hygiene - also clipping nails, shaving other **private parts**.. i perosnally think everyone should do it.. imagine how it feels on a busy train or bus wid #Mr' next to u n his smelly jungle!!
Smelly jungle? If you wash frequently you won't smell. Whether you shave your arm pits or not if you don't wash you'll stink. I don't shave my armpits and I won't. I'm a man. I always smell good. The secret to that is wash twice daily with soap and shower gel then spray yourself with deoderant.
As for hairy chest, alot of women like it but only in moderation. From the women I've known they hate excessive hair on the chest.