There are many butterfly enthusiasts lurking around CS or you can try www.butterflycircle.com a local butterfly forum. Many experts in butterflies there. Got a moth expert there as well.
;p
btw, most of the butterfly lovers i know don't really encourage people to 'keep' butterflies. They just observe them in the nature or grow some plants to attract them to nectar (feed) on. I hope that's your intention too. Capturing/keeping is a strict :nono:
enjoy the beautiful jewels!
If you have a garden, it isn't too difficult to attract butterflies, especially in a country like Singapore where there is no real winter and insects are present all year round. Simply plant flowering shrubs in the garden (try to observe which species in parks actually attract butterflies). Also, do some research on which plants are host plants for most butterflies (the above-mentioned butterflycircle.com is a great place for info) and plant some of those too. Finally, one important rule; do not use insecticides anywhere around the house and especially in the garden. You will find that after a period of time your garden is a "popular hangout" for the local insect population!
Oh yes, it should. Ripe fruit will attract all kinds of insects (flies, hornets, beetles), not only butterflies. But this is part of the wonder of having nature close to home!
Hibiscus is a great start, try a variety of other plants too. Sorry I can't help much with this because I'm not familiar with butterflies and their favourite plants. Try to observe which types butterflies in the wild frequent.