So how are your breeders?
1. I forgot to tell you that you don't want mosquitoes that lays in clean clear water. They are the carrier of dengue virus. (I'm not sure if Singapore has dengue issues, but we do! So just in case .....) I think mosq that breeds in dirty water are the carriers of malaria. I suggest that you net and freeze them before they become air born or quickly kill them.
2. You don't have to wait until they make bubble nests. Look at the way they swim - all over the tank, in an "S" way, showing off and sort of "dancing". It never fails, they will eventually spawn. Both breeders swim this way when they want to spawn. So don't worry too much ....
You do know how they hold their stand when they want to fight, don't you? .... If you're not sure go to youtube and look at the courtship of bettas. Then compare it to videos of only betta (not spawning).
Your climate is similar to mine and The Thai's. You can use any method and container/tank. Just remember that smaller containers need more care (feeding, pwc, etc). Taller plastic containers are harder to monitor fry, specially if you use floating plants or whatever.
Her's my method: dark 50cm diameter x 20 cm buckets. Fill it up about 10cm, use a lot of plants at least half of bucket, put some dry leaves (sometimes ketapang). Sometimes I would put in a cup of daphnia (for infusoria starter). I age all that between 1 - 4 weeks.
For bad breeders/fathers, I use a 25x25x10cm plastic box. Fill it half full with the above aged water, use a lot of plants. Then I put in the breeders. Usually after 2 weeks, I move the fry to a bigger container, depending on how many fry survive.
I suggest that you determine how much time and energy you're willing to put in. Then decide on size of container and method of breeding. Breeding is easy. It's rearing the fry that's hard.