Well, AIS is less famous than those from ESF (english School Foundations, but fees can be rocket high) in HK. Think its in the mid-range in terms of quality & pricing. As for location, Kowloon Tong is one of the most affluent areas on the Kln Peninsula, so don't expect rental rates will be far cheaper than in the HK South. Try
http://www.hkwithkids.com/schools.htm#esf to see more.
There is not a "furnished apt" category in gohome.com, unless specified in the flat's bio, otherwise pls dont expect its a furnished one. But gohome.com was already the best & most thorough search engine for flats in town. You may contact a licensed real estate agent (Midland, Centaline, Century 21, Ricacorp are trust-worthy ones) if you have special needs.
Furnishing rates vary depending on the flat's size, layout, material, & most importantly yr expectations & budget. I've some good interior design referral on hand if you want to have a free quote. Hope it helps!