Good lighting at the Serangoon temple should be in the morning. Used to go there at 9am. After that, move on the road with them. Good high angle is Selegie Road overhead bridge next to Selegie Arts centre. The poccession walk under the bridge. Afternoon will reach Tank Road Temple for the afternoon light.
Be prepared to do a lot of walking. Those carrying kavadi walks only once, photogs walk up and down a many times.
Travel light, with only the equipment you need. I prefer a super wide for shots yp close and a tele (80-200) to close in on the facal exapression. Plus a flash, a monopod and batteries.