For nomal 1 phase meter home:
1 home socket = 13A.
1 rig 1200w = 5A.
so you can go max 2 rig per socket, unless u route the 20A MCB (mini circuit breaker) from the DB which is usually used for airconds to power your rigs.
too expensive. see here for example: http://www.aims.com.my/colocation-services/co-location-package-and-pricing-in-malaysia/
unless you're going to have an ASIC farm of 2TH/s and above, i don't think it's feasible to use a datacenter.
if mining LTC or other alt coins, the electricity is going to be really expensive there. hence, i guess it's better to rent an office shoplot and put them there. a shoplot if im not mistaken has 200A, so can house maximum 30 rigs there + aircond. you wouldnt want to put more, it's risky as it's nearing the 200A current. 1 shoplot can easily get around MYR1000. cheaper than datacenter.
but well, for datacenter, there's 'free' aircond and 'free' internet already with 24/7 power. (the MYR3000 u paid every month is for that )