Can I do vacuumlo,vacuumdb and reindex in live production system without any downtime in postgres database
"reindexdb" takes the most stringently lock, and is the only thing likely to be causing downtime.

Unless you have evidence that it is necessary, just stop doing the "reindexdb".  It might be necessary to do it once, in order to get you out of the hole, but shouldn't be necessary to do each time you do "vacuumlo".